Actor Mark Rylance has resigned from the Royal Shakespeare Company over its sponsorship deal with oil company BP.
Rylance, in a resignation letter, said he was quitting to "lend strength" to progressive voices in the RSC.
The RSC said it is "saddened" by Rylance's departure but that corporate sponsorship is "an important part" of its funding.
In 2016, he said he was likely to quit unless the RSC dropped its ties to BP.
The oil company declined to comment on Rylance's personal choice, but said it remains committed to sustainable energy solutions and is "proud" of its partnership with the RSC, held since 2011.
This includes funding a £5 ticket scheme for 16-25 year olds, with around 10,000 tickets being sold through the initiative each year.
Rylance, an Oscar-winner and associate artist with the RSC for 30 years, has been a longstanding critic of the sponsorship agreement.
In 2012, he signed a petition stating BP's sponsorship deal allowed the company to "obscure the destructive reality of its activities" which he said threatened the future of the planet.
"Half the greenhouse gases in the atmosphere currently warming our planet have been emitted in the last 30 years," he wrote in today's resignation letter.
"BP has made the third-biggest contribution to climate change of any private company in history.
"I do not wish to be associated with BP any more than I would with an arms dealer, a tobacco salesman or anyone who wilfully destroys the lives of others alive and unborn. Nor, I believe, would William Shakespeare," he added.
Rylance last appeared on stage for the RSC in 1989, when he had the lead roles in both Hamlet and Romeo and Juliet.