A judge sentenced Jamie Waylett, who played Hogwarts bully Vincent Crabbe in six of the films, to two years behind bars. Prosecutors said the 22-year-old was part of a small gang that took part in the riots in north London on Aug. 8.
A jury at London's Wood Green Crown Court found Waylett guilty Tuesday of violent disorder, but acquitted him of another charge of intending to destroy or damage property with a fire bomb he was holding.
Waylett has a previous conviction for growing marijuana.
The Associated Press contributed to this report.