David Klein was born in Toronto, Canada, to a Jewish-Italian family. He is the son of Paula Klein, a social worker, and Mary Lou Fassel, a family lawyer. Growing up, Klein performed in many youth theatre musicals and studied drama at Etobicoke School of the Arts in Toronto. After high school, he moved to New York City where he later graduated from NYU Tisch.
His first appearances include the critically acclaimed short film,
Gloria (2013),
Murdoch Mysteries (2008), and
The Expanse (2015).
Klein made his feature film debut alongside
Nicolas Cage in A24's
Dream Scenario (2023) directed by
Kristoffer Borgli. He will also appear in the upcoming Disney+ film
Out of My Mind (2024) and Entertainment One's
Everything's Going to Be Great.