Sir Sam Mendes fears theatre workers could "fall through the cracks" amid the coronavirus pandemic.
The award-winning filmmaker has urged movie stars, streaming services and studios to lend their support to theatre workers, who he believes have been largely neglected by the UK government.
He told BBC Radio 4: "There's a great danger in this rescue package and in the arts world generally that the people who create the actual work fall through the cracks.
"These are the people who actually make the shows that the public pay to see.
"So there's a danger that you're going to have some very healthy arts administrations, accounts departments, foyers and bookshops, but you're not going to have any work to put on the stages, because the people who make that work, who make up 70 percent of the theatre industry's employees, are being effectively ignored."
The acclaimed director launched the Theatre Artists Fund earlier this month, with a £500,000 donation from Netflix, in a bid to help people through the crisis.
However, he's stressed that much more needs to be done.
Sam said: "I wanted to make sure that some of the people who were right on the edge, who might indeed during this period choose to leave the industry entirely, could be protected. But this is really a drop in the ocean."
The UK government recently announced a £1.57 billion rescue package for the arts industry, with the aim of saving venues across the country.
But the '1917' director admits he may have been forced to quit the business if he'd faced a similar challenge early in his career.
He explained: "I don't think I would have been able to remain part of the theatre world at that point in my career."