And sure enough, the pair have come to blows spectacularly on Twitter, with Kelly branding the rent-a-gob a "c***".
It all started on Thursday morning when Kelly found about about some comments Katie made about her mum Sharon's surgery last year.
"U R a hypocritical vile human that is addicted 2 attention U R so insignificant! Don't you ever talk about my mother again!#India," she raged.
"Think John Lennon said it best “One thing you can't hide is when you're crippled inside.” I feel sorry for you & Ur ignorance!"
But Katie hit back by comparing Kelly to another one of her foes Peaches Geldof, saying that she is only famous because of her parents.
"Just like Peaches and Jesus, Kelly has done well due to a famous parent," she tweeted.
"Just like you can't help the parents you came from neither can I! I don't see you on a @Forbes list I work my bum off nice try…" Kelly bit back.
"I know that what I am about to say is unbecoming of a lady & Im sorry to say this but I can't lie you are a massive #C***."
At which point Katie replied again, tweeting: "No problem Kel. No one ever mistook you for a lady sweetie pie."
Kelly then retorted: "You can shove your sweetie pie up your ass you insignificant tw*t! Karma will get you! bl**dy hell you are so such a sad ass!"
She added: "actually made my night that @KTHopkins considers herself a lady when I think of her a desperate sad old bitter child is what comes to mind (sic)."
Now ladies, can't we all just get along nicely? No? Ok then, we'll butt out.
Lord Sugar and Tulisa
Lord Sugar didn't hold back when he tweeted Simon Cowell to tell him exactly what he thought of Tulisa on 'The X Factor', telling him: "She knows nothing and talks rubbish". She responded by calling him an "ugly hobbit" and a "miserable old man". He had the last laugh though when she was axed from the show a few months later.
Sharon Osbourne and Steve Brookstein
Mrs O just couldn't keep her true feelings about 'X Factor' contestant Steve Brookstein secret any longer during the final of the first series in 2004. She labelled the eventual winner a 'fake' and 'not what he seems' during her live tirade. Nine years on, and Sharon still bares a grudge, labelling him a 'little pillock' and a 'ball-less b*****d" upon her return to the show. Steve later tweeted: "Not looking forward to Sharon Osbourne returning to our screens will have to avoid itv."
Robbie Williams and Gary Barlow
They may be best pals again now, but for a long time things weren't pretty between the Take That-ers, after Robbie quit the group in 1995 and then failed to turn up for a televised reunion in 2005. He later said: "My problem has always been with Gary. It was always with Gary. I wanted to crush him. I wanted to crush the memory of the band - and I didn't let go. You know, even when he was down, I didn't let go. And for that I sincerely apologise." The pair made it up and recorded duet 'Shame' in 2010, before Robbie rejoined Take That for a short stint.
Kerry Katona and Brian McFadden
There isn't an insult Kerry Katona hasn't used to describe her ex husband Brian McFadden after their marriage ended in 2004. But Brain has also fought back, infamously referring to Kerry as 'some pr*ck' on Twitter. Most recently she said: "What pisses me off is that when he does fall in love, the kids come second. And that's why I think he's a w**ker." Charming.
Sharon Osbourne and Dannii Minogue
Bet you can't name a single contestant from series four of 'The X Factor' in 2007 - that's because the whole series was dominated by the almighty cat fight between Sharon Osbourne and Dannii Minogue. Shazza called her "a spoon with hair" when she appeared on Graham Norton show, adding: "She wasn't so much a dim bulb as a bulb in a power cut. F***ing usless." Sharon later quit the show as Dannii "became too unbearable", comparing her to "a mosquito that wouldn't go away."
Simon Cowell and Cheryl Cole
Once the best of friends, the pair famously fell out when Cheryl was axed from the US version of 'The X Factor' after just four days of auditions. As of July 2013, <a href="http://www.huffingtonpost.co.uk/2013/07/15/cheryl-cole-simon-cowell-x-factor-usa-sacking_n_3596824.html?utm_hp_ref=cheryl-cole" target="_blank">Cheryl was locked in a court battle</a> trying to get compensation for her sacking, and instructed her lawyers to quiz Simon on how much he earns. However, the pair are now friends again, with <a href="http://www.huffingtonpost.co.uk/2013/07/02/cheryl-cole-lady-simon-cowell-birthday-present_n_3531957.html?utm_hp_ref=cheryl-cole" target="_blank">Cheryl thanking her former boss for a gift he sent for her 30th birthday </a>in June 2013. He also tweeted: "We are close friends again and I adore her."
Nicki Minaj and Mariah Carey
All hell broke loose on the 'American Idol' set in 2010 when Nicki Minaj tired with Mariah Carey's 'divaish' ways and<a href="http://www.huffingtonpost.co.uk/2012/10/03/nicki-minaj-mariah-carey-row-video_n_1934808.html" target="_blank"> allegedly threatened to violence against her in behind-the-scenes footage</a> leaked to TMZ. "I told them I'm not f*****g putting up with her f*****g highness over there. I'm gonna knock you out," she screamed. Six months of barbed comments, eye rolling and awkward tension followed, before they both quit the show after just one series.
One Direction and The Wanted
We don't even know where to start with the beef between these two boybands. So many insults have been traded since both of them cracked America that we've lost track.
Taylor Swift and Kanye West
Kayne West infamously hijacked Taylor Swift's acceptance speech at the 2009 Video Music Awards, interrupting her to say, "I'm really happy for you. I'ma let you finish, but Beyoncé had one of the best videos of all time." Swift was dumbstruck by the incident and it seemed as if she didn't want to get into it with the rapper. "I don't know him, and I've never met him, so..." she said. "I don't want to start anything because I had a great night tonight." A year later she was literally singing a different tune. At the 2010 VMAs she p<a href="http://www.hollywoodlife.com/2010/09/13/taylor-swift-kanye-west-mtv-video-music-awards-youre-still-an-innocent-time-we-had-a-toast/" target="_hplink">erformed her new song</a> "You're Still an Innocent," a reference to the previous year's incident with West, basically calling him immature. "Thirty-two and still growing up now / who you are is not what you did / you're still an innocent," she sang. Kanye didn't have any right to fire back, but of course he did. At a concert in New York City, <a href="http://www.popeater.com/2010/11/24/kanye-west-concert-taylor-swift/" target="_hplink">West blasted Swift to his fans</a>: "Everybody needs a villain, don't we? We need to blame someone at all times ... I was emotional, that was not exactly the way I wanted to word it, but I wrote it, I rode it, just as Taylor never came to my defense in any interview, and rode the waves and rode it and rode it." The feud seems to have blown over, as Swift wore a blouse from Kanye West's spring 2012 collection in the <a href="http://www.hollywoodlife.com/2012/03/07/taylor-swift-kanye-west-design-harpers-bazaar-australia/" target="_hplink">pages of <em>Harper's Bazaar.</em> </a>
Katie Price and Kelly Brook
Katie Price sparked outrage when she labelled Kelly Brook a heifer after seeing snaps of her in a bikini. The pair threw a string of insults at each other over the following weeks before Katie then publicly hit out at Kelly's boyfriend (and her ex), Danny Cipriani, warning her that he'd never stay faithful. Turns out the Pricey was right, as sure enough the couple split soon after, when it was revealed he had been sending saucy messages to other women.
Karen Barber and Jason Gardiner
'Dancing On Ice' judges Karen and Jason created a piece of TV gold when their obvious hatred for each other reached boiling point during one live show. <strong>Hit play on the video to the left to view the spat in full. </strong>
Cheryl Cole and Lily Allen
These two are never afraid to tell people what they think, so it's little surprise they've had a showbiz spat. It all started when Cheryl misunderstood that Lily's song 'Cheryl Tweedy' was not intended as a compliment. She later infamously called her a 'chick with a dick' in 2007. Lily later got her own back by tweeting about Chezza's 2003 conviction for assault.
Lady Gaga and Perez Hilton
Things have turned sour between former pals Lady Gaga and Perez Hilton - the 'Applause' singer recently claimed the celebrity blogger mocked her after she had her hip accident sending by her a picture of herself in a wheelchair with the word 'karma' written on it, along with a image of Madonna pointing a gun at her. Gaga later tweeted that Perez was stalking her when he turned up at her apartment building. He claimed is was merely a coincidence during a househunting trip, and added that it was "too painful for him to go into detail about why he chose to no longer make her a part of his life."
Katie Price and Peter Andre
Remember when Katie Price and Peter Andre were happy? We know it's hard to imagine now, giving the mauling they have given each other in the press since their nasty split in 2009. There have been claims of (strongly denied) affairs, court cases and constant digs during TV appearances. Although Katie did congratulate Pete on his girlfriend's pregnancy in 2013.
Denise Van Outen and Johnny Vaughn
The former breakfast telly BFFs fell out when Denise joined Johnny's radio show, only to quit soon after. While Johnny claims there is 'no rift', Denise told us: It was a very strained relationship at the time, for whatever reason. No I'm not joking. It just wasn't the relationship we had previously on TV. He wouldn't let me speak, would tell me when I should and shouldn't speak, and would also constantly not mention that we were joint presenters."
Elton John and Madonna
The feud in question began in 2002, when Elt labelled Madonna's song for the 007 film, 'Die Another Day,' as 'the worst Bond tune ever'. As the spat escalated over the years, he publicly called her a 'c*nt' and a 'f***ing fairground stripper', before they <em>finally</em> made it up in 2013.
Cher Lloyd and Cheryl Cole
Cher Lloyd may have been 'right up Cheryl Cole's street' after the Girls Aloud star mentored her on 'The X Factor', but the mini-me didn't take too kindly to Cheryl losing touch after the show. <a href="http://www.huffingtonpost.co.uk/2012/02/14/cher-lloyd-cheryl-cole_n_1276220.html?ref=uk-celebrity" target="_blank">Cher made a dig about her former pal</a>, saying she would only do a duet with Cheryl if she didn't use autotune, prompting <a href="http://www.huffingtonpost.co.uk/2012/02/15/cheryl-cole-cher-lloyd-twitter_n_1278516.html" target="_blank">Cheryl to hit back on Twitter</a>. "Be Careful who you kick on your way up .. They kick you twice as hard on your way back down.. #unappreciationisugly," she wrote. Ouch!
Miley and Selena Gomez & Demi Lovato
Disney starlets do not play nice. In 2008, teen queen Miley Cyrus went head to head with Selena Gomez and Demi Lovato. BFFs Selena and Demi used to make goofy videos they would post to YouTube, much to the chagrin of Miley as it turned out. Miley and her BFF Mandy made a parody video where they mocked the other girls, making fun of their makeup and the gap in Demi's front teeth. The feud appeared to come out of nowhere. "To be honest I don't know what happened," <a href="http://newsroom.mtv.com/2008/08/01/the-miley-cyrus-selena-gomez-demi-lovato-feud-nonexistent/" target="_hplink">Selena told MTV</a>. "I though we were okay, but to be honest, I don't even know [Miley and Mandy]. And Demi has never met Miley. It's interesting -- that's all I'm going to say about it." They all eventually made up and became friends. <a href="http://www.aceshowbiz.com/news/view/00021443.html" target="_hplink">Miley addressed the feud in a YouTube video in 2009: </a> "So everyone's thinking there's a big feud between me and Selena and Demi. Actually, I'm going to have meatloaf with Demi tonight. I'm riding my bike to Demi's house. So I'm going to be partying with Demi 'cause we're friends, and I love her and she is always there for me. She is one of my bestest friends."
Kelly Osbourne and Christina Aguilera
These ladies need to learn to keep their comments to themselves. Back in the day, Christina Aguilera apparently used to call Kelly Osbourne fat, and now that Kelly has slimmed down and Christina has gained a few pounds the tables have turned. Osbourne made sure to call attention to the singer's weight gain, not once, but twice in 2011. "Maybe she is just becoming the fat bitch she was born to be. I don't know. She was a c**t to me. And she bought my house," Osbourne said <a href="http://www.huffingtonpost.com/2011/08/04/kelly-osbourne-calls-christina-aguilera-a-fat-bitch_n_918063.html" target="_hplink">during an episode of "Fashion Police" that aired in August.</a> "She called me fat for so many f***ing years, so you know what? F**k you! You're fat too." Then in October, the <a href="http://www.huffingtonpost.com/2011/10/17/kelly-osbourne-i-was-never-as-fat-as-christina-aguilera_n_1015490.html" target="_hplink">singer was again the topic of discussion on the show: </a> "Lady Marmalade got into the peanut better again," quipped co-host Joan Rivers when criticizing Aguilera's too-tight outfit. "She called me fat for years, I was never that fat," Osbourne said and later added, "Trust me, I'm a 2/4. That is not a 2/4."
Chantelle Houghton and Alex Reid
Thanks to their love of a magazine deal, Chantelle Houghton and Alex Reid's war of words even began before the pair had actually split up. She claimed Alex had refused to stop dressing as female alter-ego Roxanne, and said he turned their house into a sex dungeon, while Aled later claimed that he had been stopped from seeing their daughter Dolly.
Lady Gaga and Madonna
Madonna was not too pleased when Lady Gaga released 'Born This Way' in 2011, believing she'd copied her hit 'Express Yourself'. "Imitation is the highest form of flattery," she said, later adding: "I'm a really big fan. I'm glad that I helped write it." Gaga hit back while on-stage one night: "It sometimes makes people feel better about themselves to put other people down or make fun of them or maybe make mockery of their work." Now Madge claims she "loves" Gaga and wants to duet with her - something with the Lady has since turned down.
Mariah Carey and Eminem
Is there anyone Eminem hasn't feuded with? Eminem and Mariah Carey began to spar after he claimed that they used to have a sexual relationship. Mariah denied the relationship, telling Larry King, "I hung out with him, I spoke to him on the phone. I think I was probably with him a total of four times. And I don't consider that dating somebody." Mariah later mocked his claim in her video for "Obsessed," which featured an Eminem look-alike who was obsessed with her. The rapper retaliated with a number of songs that mentioned Carey and threatened to release nude photos of the singer as well as voicemails to prove they dated. In the song "The Warning" he raps: "Shut the fuck up before I put up all the phone calls you made to my house when you were "Wild N' Out" before Nick, when you was on my dick and give you something to smile about."
Lauren Conrad and Heidi and Spencer
"You know what you did," Lauren Conrad screamed at Heidi Montag on an episode of "The Hills." Lauren and Heidi's friendship began to dissolve in 2007, when Heidi started dating Spencer Pratt. "He's a sucky person," she infamously told her one-time best friend. Heidi chose a relationship with Spencer over a friendship with Lauren and spread a rumor there was a<a href="http://www.justjared.com/2008/05/01/heidi-montag-lauren-conrad-feud/" target="_hplink"> Lauren Conrad sex tape floating around. </a> Heidi tried to repair things with Lauren, but she wasn't having it. "I want to forgive you and I want to forget you," Lauren told her as <a href="http://www.sheknows.com/living/march-madness-mix-up-gallery/cry-faces/lauren-conrad-3" target="_hplink">mascara ran down her face</a>. The feud eventually ended but they never repaired their friendship. As Spencer began to fade into obscurity he tried make himself relevant by burying the hatchet with Conrad, <a href="http://tv.yahoo.com/news/lauren-conrad-planning-ignore-spencer-pratts-apology-000504559.html" target="_hplink">wishing her a happy birthday</a> on Twitter in February 2012.
Ciara and Rihanna
Rihanna and Ciara - who both dated Chris Brown in the past - got into a heated public spat in February 2011. First Ciara made a dig at Rihanna on 'Fashion Police', saying: "I ran into her recently at a party. She wasn't the nicest. It's crazy because I've always loved and respected what she's done in fashion. It wasn't the most pleasant run-in." When Rihanna heard what Ciara had said, she fired back on Twitter. "My bad Ci, did I forget to tip you? How rude of me.... You gangsta huh? Ha." They volleyed insults and threats at each other and then Rihanna called a truce. "Ciara baby, I love you girl! You hurt my feelings real bad on TV! I'm heartbroken! That's why I retaliated this way! So sorry! Let's make up." Ciara accepted the apology and that was that.
Tom Cruise and Brooke Shields
In 2005, Tom Cruise seemed to have lost his marbles when he jumped on couches on Oprah's talkshow. He then lashed out at actress Brooke Shields, while on the 'Today' show, telling Matt Lauer that Shields should not have taken antidepressants to combat the postpartum depression she was suffering from after the birth of her first child. Cruise, a Scientologist who shuns psychiatry, insisted the depression could be treated with "vitamins and exercise." Shields responded by writing an <a href="http://www.nytimes.com/2005/07/01/opinion/01shields.html" target="_hplink">op-ed piece in the <em>New York Times,</em> writing</a>: "I'm going to take a wild guess and say that Mr. Cruise has never suffered from postpartum depression ... And comments like those made by Tom Cruise are a disservice to mothers everywhere ... If any good can come of Mr. Cruise's ridiculous rant, let's hope that it gives much-needed attention to a serious disease." Cruise later apologized to <a href="http://www.people.com/people/article/0,,1531255,00.html" target="_hplink">Shields, the actress told Jay Leno </a>a year later. "He came over to my house and he gave me a heartfelt apology. And he apologized for bringing me into the whole thing and for everything that happened," she said.
Chris Brown and Drake
The mother of all fights broke out between Chris Brown and Drake as the pair started a brawl in a New York nightclub, allegedly over Rihanna, who they'd both dated.
Hilary Duff and Lindsay Lohan
Take two Disney starlets and one prepubescent popstar and you have a recipe for one of the most discussed celebrity feuds of the 2000s. Back in 2002, Aaron Carter reportedly broke up with or cheated on Hilary Duff, who he was dating for two years, to hook up with Lindsay Lohan. The 15-year-old Casanova then left Lohan to get back together with Duff. Though the girls should have been furious with Carter, they instead turned on each other. Their feud played out in the pages of magazines with both actresses <a href="http://today.msnbc.msn.com/id/8669450/ns/today-entertainment/t/lohan-says-duff-rebuffed-her-peace-attempt/" target="_hplink">taking shots at each other for years. </a> By 2007 the girls put their past behind them and made up. "We are both adults and whatever happened, happened when we were young," Duff <a href="http://www.people.com/people/article/0,,20033534,00.html" target="_hplink">told <em>People</em></a>. "It's over."
Will.i.am and Perez Hilton
Gossip blogger Perez Hilton was confronted by the Black Eyed Peas at the Much Music Video Awards in 2009 and began hurling insults at Will.i.am and the rest of the band. Perez was <a href="http://www.huffingtonpost.com/2009/06/22/perez-hilton-called-willi_n_219088.html" target="_hplink">punched in the face</a> by Will.i.am's manager and the blogger later tweeted, "I was assaulted by Will.i.am of the Black Eyed Peas and his security guards. I am bleeding. Please, I need a police report. No joke." Will.i.am later denied Hilton's claims and Hilton shot back with a 12-minute video blasting the Black Eyed Pea as a "disgusting human being" and "a fucking liar." Perez later sued Will.i.am's manager and a s<a href="http://wonderwall.msn.com/music/perez-hilton-black-eyed-peas-manager-settle-suit-1537413.story" target="_hplink">ettlement was reached.</a>
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