Vellian Crolwer is the head master of the Obisk blue dorm. Initially scheming and underhanded in attempting to expel Jaden Yuki due to loseing to him in the beginning. He was the main antagonist of the first half of the first season before the Shadow Riders debuted.
He carries a duel disk worn horizontally across his torso, which has a motion sensor that automatically ejects cards from his Deck when he is ready to draw.
When first introduced he is a tough teacher who belives the oblisk blue dorm is the best and hates weak sliver students. He tries to get Jaden kicked out but fails badly. Eventully he respects him and when he has a rematch with Jaden where he admits he doesn't want to see his students go.
He first appears watching the duel achidemy exams. Someone tells him a new student named Jaden has arrived. Crowler desides to use his own deck rather than the test ones and ends up giving Jaden a hard time. Jaden ends up beating him by using the winged Karbio card.