Jack and Judy Geller (Elliott Gould and Christina Pickles)(01 of11)
Open Image ModalWhether they're being wildly sexually inappropriate, insensitive to their daughter or putting everybody in their place, the arrival of Monica and Ross's parents always guarantees an eventful episode.
While Jack and Judy are the recurring characters with the most guest appearances (20, if you're interested), we'd still like to have seen them a little more often. (credit:Warner Bros via friends.wikia.com)
Susan Bunch (Jessica Hecht)(02 of11)
Open Image ModalSadly, Susan was never seen past the sixth series of Friends, which is a real shame as we loved her long-standing frosty relationship with Ross.
We particularly enjoyed her blasé putdowns, which she managed to deliver with an iciness we aspire to. (credit:Warner Bros)
Bonnie (Christine Taylor)(03 of11)
Open Image ModalA woman who will shave her head in the middle of a beach holiday just because someone planted the mere suggestion in her mind. Amazing.
We know Rachel wouldn't have been thrilled by the prospect, but we definitely wouldn't have minded Bonnie sticking around for more than two episodes. (credit:Warner Bros)
Eddie Menuek (Adam Goldberg)(04 of11)
Open Image ModalAs Chandler's brief time living with Eddie grew to a close, he became an even more odd creation, but it would have been great if the writers had cranked things up another notch with his strangeness, or at the very least showed us what happened when he was shown the door.
Where did he go? Who does he live with now? How is his cherished pet, the goldfish cracker? These are the questions we need answers to. (credit:Warner Bros)
Amy Greene (Christina Applegate)(05 of11)
Open Image ModalIt's always great when one of the characters' family members arrive, because they remind you of how they used to be – and that's never more true than when Rachel's sister Amy arrives on the scene.
Amy is even more spoilt, and cares less about other people's feelings, than Season One Rachel, though with slightly less iconic hair. (No offence to Christina Applegate, of course). (credit:Warner Bros via friends.wikia.com)
Frank Buffay Jr and Alice Knight Buffay (Giovanni Ribisi and Debra Jo Rupp)(06 of11)
Open Image ModalJoey was the character who went on to end up with his own spin-off, but we think it definitely should have been Frank and Alice.
Who honestly wouldn't want to watch a show about a man who marries his home-economics teacher, then raises triplets – that his sister gives birth to – with her? It would have been an Emmys shoo-in. (credit:Warner Bros via friends.wikia.com)
Amanda Buffamonteezi (Jennifer Coolidge)(07 of11)
Open Image ModalPhoebe and Monica made the unwise decision to "cut out" Amanda, but frankly we'd have happily seen her stay until the finale, for the dancing alone. (credit:Warner Bros)
Mr Heckles (Larry Hankin)(08 of11)
Open Image ModalThe great thing about Mr Heckles, especially watching earlier series back, is that it reminds you just how young the characters were – and what a nightmare that group of twenty-somethings would have been if you lived near them... (credit:Warner Bros)
Erica (Anna Faris)(09 of11)
Open Image Modal...conversely, by the time Erica arrives in the tenth season, her youthful naivety proves just how far the six principal characters have come.
We can't help but feel the fabulous and funny Anna Faris was criminally underused, and it would have been nice to see her stay around exploring New York for a while longer, rather than her few fleeting appearances. (credit:Warner Bros via friends.wikia.com)
Gunther (James Michael Tyler)(10 of11)
Open Image ModalTrue, Gunther did feature in quite a lot of episodes, but how much do we know about the man behind the fluorescent hair?What does he do at night? Where does he live? What are his hopes? His dreams? His fears?Actually, it's probably best not to know... (credit:Warner Bros)
Marcel (Katie the Monkey)(11 of11)
Open Image ModalJust because. (credit:Warner Bros via friends.wikia.com)