Professor Clyde is a recurring non-playable character Trevor games.
Trevor 2: The Search for Chester Chipmunk
Clyde oversees the PC Lab outside Rodenttown.
Trevor 3: The Search for Chester Chipmunk
Clyde's role is greatly increased in the third game. He is the one who initially informs Trevor of Shadow's intent to conquer North Island and (along with Chester) accompanies him to the island. This makes him one of the few characters from the previous games to appear in Trevor 3.