According to entertainment website Vulture, the 70-year-old actor harassed writer Jessica Teich over two to three years while she was working on a show he was producing.
At one point, she said she was summoned to the Oscar winner's trailer on a set in 1987 and found him with his penis exposed.
A former male model accused the actor of sexually assaulting him in 1981. The Hollywood Reporter published an interview with Scott R. Brunton, who said he was groped by the former Star Trek actor when he was 23 and Takei was in his 40s.
Takei allegedly tried to remove Brunton's underwear after the latter passed out from drinking.
Brunton was inspired to come forward after reading statements of support made by Takei in the wake of sexual-assault claims by others.
Richard Dreyfuss' son said Kevin Spacey groped him when he was 18, prompting his dad to tweet that he was "incredibly proud" of his son.
"When I read about his support for his son, which I would never question, I remember thinking, 'But wait a minute, this guy (Takei, who had slammed abusers online) harassed me for months'. It just seemed so hypocritical."
Former ER actor Anthony Edwards wrote a post on publishing platform Medium saying he had been molested by producer Gary Goddard, who acted as a mentor and personal manager during his early career.
Edwards said Goddard preyed upon him because he was vulnerable and that he raped his best friend.