The disgraced comedian Bill Cosby and the director Roman Polanski have been expelled from the Academy of Motion Picture Arts and Sciences following a vote by its board of governors on Tuesday night, the organization announced on Thursday.

The action comes after Mr. Cosby was found guilty last week of sexually assaulting a former Temple University employee, though many dozens of women have stepped forward, claiming he drugged and assaulted them too.

Mr. Polanski, the Polish-born filmmaker who won the Oscar for best director in 2003 for “The Pianist,” has been a fugitive from the United States since 1978, after he fled the country while awaiting sentencing for statutory rape.

Last year, the academy adopted a code of conduct that reads, in part, “There is no place in the academy for people who abuse their status, power or influence in a manner that violates recognized standards of decency.”