Originally Posted by ravenheart
Circle II Circle
Yes, these, plus here's a few others:
Circus Maximus (guy has a big range, but has a really amazing low register he uses a lot on ballads and stuff)
Kamelot (Khan is pretty much the poster child for a power metal vocalist with a low(er) range)
Wuthering Heights (Same vocalist as Astral Doors/Lion's Share)
More progressive metal bands that have lower-range vocalists:
Evergrey (Tom S. Englund is one of my favorite singers period)
Later Fates Warning/Redemption (Ray Alder
and Circle II Circle also translates to Zak Stevens-fronted Savatage
Oh, and you might want to try Sinner. It's more hard rock-ish stuff, but Mat Sinner has a pretty low voice.
Also the new Avantasia albums have a lot of deeper vocalists for a power metal album, and Tobias Sammet's vocal range is deepening over time.