Maynard James Keenan from Tool and A Perfect Circle
Zack de la Rocha (Excelent lyrics and one of the few rappers I actually can stand
)
Brian from Catharsis (Noone can scream like him, and his lyrics are just incredible)
Simen Hestnes, the clean vocals on Dimmu Borgir
Mikael Åkerfelt from Opeth (I just love they way he changes between clean vocals to deep demonic growling)