Every team needs a guy (or girl) to wave the flag, and DC quietly introduced one less than a year ago in its Justice League book (pre New 52). If you're not familiar with him, allow me to draw your attention to Dark Crow (full name, Daniel Crow-Brings-Darkness).
I only found out about this guy a couple of weeks ago. He appeared in the "Rise of Eclipso" Justice League story which ran in issues 54 through 59 (inclusive) .
Mind you, it's quite difficult to get a decent shot of him so presumably his role was quite small. I suspect he was brought up to be little more than a pawn of Eclipso. It appears as though he can manipulate his own shadow into taking the shape of a large crow that does his bidding.
So going back to the beginning, that's four Canadian characters that DC can use: Plastique, Flying Fox, Freight Train and Dark Crow. There is one more that I want to look into, but she will require a little more research before I post about her. Nonetheless, this is a good core from which to build.
How about it, DC? Justice League Canada? ;-)