Captain Canuck, Sasquatch, and Wolverine make the list of course, but here's a couple greats you've probably never heard of:
The Polka-Dot Pirate:

Imagine being a Canadian criminal captured by the Pirate, “The Polka Dots came out of the darkness, she was a demoness, at least 5’3, and she was a pirate…in polka dots!”
but the most uniquely Canadian superhero of them all....
Red Ketchup

Born an albino, Steve Ketchup was the son of Polish immigrant, a violent alcoholic who beat his son regularly to "educate" him. He used to force Red to play chicken with oncoming trains to help him "become more of a man." and would beat Red if he dodged the train too quickly. His father suffered a massive stroke after beating Red's older sister for her hippy lifestyle. As soon as Red was sixteen he enlisted to get away from his father, and was sent to Vietnam, where he became heavily decorated. After the war he joined first the Detroit police force, and then the F.B.I.
In the Bureau, he swiftly established a reputation for being extremely violent, but terrifyingly effective. "Red" Ketchup, as he had become known, was investigating the drugs trafficker Raul Escobar, when he was exposed to a mixture of drugs including cocaine, and somehow became nearly invulnerable. Since then his boss in the F.B.I., Edgar G. Sullivan, has employed him on the most dangerous missions that the agency encounters, including tracking down Elvis, taking on a cloning racket, and going to Hell.