-Quo Vadis
-Voivod (i don't like em .....but they're good according to some)
-Warmachine (AWESOME old school band ....they only have a demo which you can download at www.warmachineonline.com)
-Annihilator
Some other bands:
Soulscar!!! ( you must check them out if you haven't already. Great melodic death metal, inspired by Death, ATG, etc...)
Maharahj (though broke up recently, still have a few albums out)
And I guess you could say North is a newcomer to the Canadian scene(shameless promotion alert! ) . You can check out a temporary website and a full length track if you want at
oops for some reason i thought nightwish were form Toronto hahah my bad ANd Soulscar yeah!!! Hahaha i talked to their drummer Chris quite a bit online back in the Napster days.. his other band Omnisight is VERY cool too with a shredder guitar player but he is not at all overbearing to the band! BTW the style of Omnisight is not really metal... almost an alternative grungy thing but no dark and depressing-ness to them.
These are my favorite bands from Canada:
Quo Vadis
Unexpect
Aphasia
Anonymus
Voidvod
Cryptopsy
Spelldown
Blinded By Faith
Trails of Anguish
Howling Syn
Winter Bestowed (rip)
Kralizec
Decayed Remains
Hanker