Hollywood actors including Benedict Cumberbatch, Sir Patrick Stewart, Bill Nighy, Chiwetel Ejiofor, Keira Knightley and Dame Kristin Scott Thomas are among leading figures from the arts world backing a vote to remain in the European Union.
Music stars Hot Chip, alt-J and Paloma Faith, authors Dame Hilary Mantel and John le Carre and fashion designer Dame Vivienne Westwood are also among the 282 figures supporting a Remain vote.
The group, including Oscar-winning director Danny Boyle and poet laureate Carol Ann Duffy, said being part of the EU "bolsters Britain's leading role on the world stage", warning that Brexit would leave the country "an outsider shouting from the wings".
The letter comes as the Creative Industries Federation revealed that more than 96% of its members supported a Remain vote on June 23.
The signatories, also including stage and screen veterans Brian Blessed and Sir Derek Jacobi, Billy Elliot star Jamie Bell and Alan Partridge actor Steve Coogan, said: "From the smallest gallery to the biggest blockbuster, many of us have worked on projects that would never have happened without vital EU funding or by collaborating across borders.
"Britain is not just stronger in Europe, it is more imaginative and more creative, and our global creative success would be severely weakened by walking away.
"And what would 'out' really mean? Leaving Europe would be a leap into the unknown for millions of people across the UK who work in the creative industries, and for the millions more at home and abroad who benefit from the growth and vibrancy of Britain's cultural sector.
"From the Bard to Bowie, British creativity inspires and influences the rest of the world. We believe that being part of the EU bolsters Britain's leading role on the world stage.
"Let's not become an outsider shouting from the wings."
Sir John Sorrell, chairman of the Creative Industries Federation, said: "The UK creative industries are key to the way we are seen by the world and deliver a massive £84.1 billion to our economy.
"Our position as a vital European creative hub is a huge part of this success - we benefit from a vast network of talented people, companies and institutions across Europe."
House of Cards creator and Tory peer Lord Dobbs dismissed the idea that culture was boosted by being in the "failing" EU.
Speaking in a personal capacity, he said: "Our creative industries are booming because of the talent that is in Britain's DNA.
"We are world leaders in so many creative areas. From theatre to literature, video games, feature films, fashion, music and so much else, British artists lead the way and are celebrated around the globe.
"It's a success that has been created by the dedication, hard work and extraordinary creative abilities of our artists, it's not because of the EU.
"Culture owes nothing to committees. Ancient Greece was the birthplace of our civilisation yet today, because of the EU's appalling policies, streets that were once filled with the world's greatest philosophers and playwrights are choked with desperate beggars and mountains of rotting rubbish.
"These are the realities of the EU. It's failing. The dream is dead. We need to move on."