The actor Kevin Spacey is “a sexual bully” who “delights in making others feel powerless and uncomfortable,” a prosecutor told a British jury on Friday. Speaking at Southwark Crown Court, the prosecutor, Christine Agnew, outlined her case against the Academy Award-winning actor, who is on trial in London facing multiple charges of sexual assault.

Ms. Agnew said that the actor’s “preferred method” of assault was to “aggressively grab other men in the crotch.” On one occasion, she said, Mr. Spacey had gone further and performed oral sex on a man while he was asleep.

The actor “abused the power and influence that his reputation and fame afforded him” to take “who he wanted, when he wanted,” Ms. Agnew said.

Mr. Spacey has pleaded not guilty to all charges.

The actor, 63, faces 12 charges related to incidents that the prosecution says involved four men and occurred between 2001 and 2013. For much of that period, Mr. Spacey was the artistic director of the Old Vic…