Lyle Lettau (born O'Donohoe) is a Canadian actor, best known for portraying Tristan Milligan, being introduced in the second part of Season 11 of Degrassi. He is known for portraying, "The Brain" in the most recent episodes of the TV show, Arthur. He is currently a senior at Flesherton's Grey Highlands Secondary School. His inspirations are Marilyn Monroe, Andy Warhol, and Lady Gaga.
2011-14 Degrassi: The Next Generation (TV Series) Tristan Milligan
2011 Degrassi: Minis (TV Series) Tristan Milligan
2008-2010 Arthur (TV Series) Alan 'The Brain' Powers
2008 Postcards from Buster (TV Series) Alan 'The Brain' Powers