Lyle Lettau is a Canadian actor, best known for having portrayed Tristan Milligan, being introduced in the second part of Season 11 of Degrassi. He is known for portraying, "The Brain" from season 12 to season 15 of the TV show, Arthur. He graduated at Flesherton's Grey Highlands Secondary School. His inspirations are Marilyn Monroe, Andy Warhol, and Lady Gaga. He is part of the band Cute Whore with Olivia Scriven.