Kevin Spacey is seeking "treatment" following claims he sexually harassed a teen thirty years ago, his publicist said.
On Monday, actor Anthony Rapp claimed Spacey had made a sexual advance toward him in 1985, when Rapp was just 14-years-old and Spacey was 26.
The House of Cards actor said in a statement that he does "not remember the encounter", but said he was "beyond horrified to hear his story".
"But if I did behave then as he describes, I owe him the sincerest apology," Spacey added.
He then addressed rumours about his sexuality, saying he now "chooses to live as a gay man".
A statement from Spacey's representatives said: "Kevin Spacey is taking the time necessary to seek evaluation and treatment. No other information is available at this time."
Roberto Cavazos, who worked with Spacey at the Old Vic, said he expected "a whole lot more" accusations in coming days.
"It seems the only requirement was to be a male under the age of 30 for Mr Spacey to feel free to touch us," the Mexican actor wrote.
"I also had a couple of unpleasant encounters with Spacey which were on the verge of being called harassment," he added.
The Old Vic theatre said it was "deeply dismayed" by the allegations against Spacey, adding "no complaints" had been made towards the actor during his time there or after he had left.
Since the claims emerged, Netflix suspended the filming of the House of Cards series, and Spacey's 2017 Emmy Founders Award was revoked.
Allegations against Spacey come in the wake of the scandal hitting Harvey Weinstein.
Since then, several claims have been made against Hollywood actors and directors, including Jeremy Piven and Dustin Hoffman.
Piven, 52, has denied allegations that he groped actress Ariane Bellamar, on the set of Entourage and at the Playboy mansion.
Hoffman, now 80, said he felt "terrible" after Anna Graham Hunter claimed he had groped her and spoken to her about sex while she was a 17-year-old production assistant on one of his film sets.Let's