The Old Vic theatre said it has received 20 personal testimonies of alleged inappropriate behaviour by Kevin Spacey during his 11-year tenure as artistic director.
Those affected said they “felt unable to raise concerns” adding he “operated without sufficient accountability”.
The acclaimed London theatre said it “truly apologises for not creating an environment or culture where people felt able to speak freely.
It will “commit to a new way forward.”
He has recently been accused of sexual harassment and assault allegations.
The first accusation was made by actor Anthony Rapp on 30 October, who claimed Spacey made a sexual advance towards him when he was 14.
In response to Mr Rapp’s claims, Mr Spacey said he has no memory of the incident and offered an apology.
On 31 October, the Old Vic said it was “deeply dismayed” to hear the allegations and sets up a confidential complaints process for people involved with the theatre.
On 3 November police in the UK confirmed they were investigating an alleged assault on a man from 2008.
Several other men and one woman have also now come forward claiming Spacey either sexually harassed or assaulted them.
Former television news anchor Heather Unruh told a press conference in Boston that her son had been sexually assaulted by Mr Spacey, at the age of 18 in a bar in Nantucket, Massachusetts, in July 2016.
She said a criminal investigation was now under way.
Spacey replaced in upcoming film
US network Netflix has axed further production of Mr Spacey’s House of Cards drama, the International Academy of Television Arts and Sciences announced it will no longer give the actor a special Emmy award, and his agent and publicist has dropped him as a client.
He has also been removed from upcoming film, All the Money in the World, which has already been shot. He will be replaced by Christopher Plummer in the role of late oil tycoon John Paul Getty.
Spacey said on 2 November he was seeking treatment, in the wake of the allegations.
A representative for the actor said he “is taking the time necessary to seek evaluation and treatment”.
They did not give any information about what kind of treatment he wanted.