Erik Per Sullivan played Dewey in Malcolm in the Middle, but the actor hasn’t been seen on screen in a long time. 17 years after Malcolm in the Middle ended, its still hailed as one of the best sitcoms of all time. The series owes a big part of its success to the talented actors who play its delightfully dysfunctional family. Malcolm in the Middle made stars out of several of its cast members. However, Sullivan left the acting business shortly after leaving the role of Dewy in Malcolm in the Middle behind.