Canada's Greatest Know-It-All is a reality series that debuted January 30, 2012, on Discovery Channel.

In the series, ten competitors claim to be "know-it-alls" and compete in a series of challenges. The challengers depend upon practical knowledge of physics, mathematics, and engineering to succeed at the challenges, as well as an ability to overcome the stereotype of know-it-alls, that a know-it-all believes that he or she knows everything and does not depend on other people's knowledge. The series is hosted and narrated by Daniel Fathers.