Both Metal and Rock have vast amount of sub-genres, especially metal, so there's something for everyone! (Well Should be). That's what makes them so great.
My favorites would be, Black Sabbath, Ozzy Osbourne (Solo stuff), Led Zeppelin, Pink Floyd, King Crimson, Jethro Tull, Nirvana, Rammstein, Oomph!, System of a Down, Serj Tankian (Solo stuff), Scars on Broadway, Leverage, Brother Firetribe, Pain, Olympus Mons, The Darkness, ..., ..., ..., ...., I won't waste time by going on.
I'll share this because Finnish Melodic Power Metal FTW!
[video=youtube;03ePbjRMjsk]http://www.youtube.com/watch?v=03ePbjRMjsk[/video]