It's hard to pick just one.
Beatles
Queen
Led Zeplin
Deep Purple
ACDC
Guns and Roses
Metallica
Pantera
Tool
Dream-Theater
System of A Down
Disturbed
Nirvana
The list could go on and on and on ...
Edit : Black Sabbath , Ozzy Osbourne, Albatross, RATM, Audioslave, Alice in Chains, Megadeth #RIPNick etc