Samuel West has claimed that a culture of low and unpaid work in the arts is a "time bomb" that will "ultimately... destroy the profession".
Writing in the acting union Equity's magazine, he called low pay or working for free "a virus" that stifled diversity.
He said it was the theatre industry's "job" to "hold a mirror up to nature".
"Unless we keep the widest possible demographic... we are building a time bomb into the future of the industry".
West, who recently directed April de Angelis's play After Electra in Plymouth, said "actors should never be asked to work for nothing when other professionals in the production are drawing salaries".
He said the usual explanation that it will "lead to visibility" should not be given "when that usually depends more on backgrounds and contacts".
West, whose parents are the actors Timothy West and Prunella Scales, said it seemed like the industry based its "economic model on those who can afford to live with their parents", which does not work.
"Talent is no respecter of postcodes, or how much your parents earn," he said.
Echoing the current campaign for more diversity in the arts - he said ultimately if the industry does not represent BAME (black, Asian and minority ethnic) people fairly "we hold up a distorting mirror; we alienate audiences and deny lots of good artists a chance of work".
"If we don't employ people with disabilities, we spread a culture of 'difference', and deny shared understanding," he said.
West appears in the second series of BBC2 comedy W1A, which returns to TV screens on Thursday.