LONDON — Russell Brand took the stand in a London court on Wednesday, giving evidence for the first time in a trial in which the popular YouTuber faces seven charges, including rape and sexual assault.

Brand’s appearance, at Southwark Crown Court, comes in the third week of a trial in which prosecutors have described the onetime comedian and actor as a “ruthless” sexual predator who either raped or assaulted six women, in episodes that prosecutors say occurred in Britain between 1999 and 2009, when he was 24 to 34 years old.

Brand, now 51, has pleaded not guilty to all seven charges and on Wednesday told the court that he although he had dedicated much of his life to “beyond reckless philandering,” he had never had nonconsensual sex.

Of his fame, Brand said that he had at times “misused that commodity very, very selfishly.” But he also told the court that “consent is fundamental, essential, necessary,” adding that for him it was “in many ways more important than sex itself.”

For most of the trial’s first…