Eminem. Too many reasons why.
These things defined music in the '00s:
Alternative rock bands who think it's funny to have overly long song titles.
Lyrically focused more on clubgoing and party concerns.
Reality competition winners (American Idol, X-Factor, etc.)
"Buzz" bands (eg Vampire Weekend, Arcade Fire, The Strokes)
Myspace and Facebook recognition
Crap defined the 2000s. Horrible, horrible decade for music. I miss the 70s and I'm only 14, lol.
Ozzy Osbourne (X)