Lifespan: 2008-2011
Reminds us of: A poorly mowed lawn

How the hell does one even part a flat top? The American Idol judge started the series with a pretty decent cut, but sometime around David Cook (if you can even remember who that dude is) Cowell evidently forgot he was filmed for national television every night sitting down. Though, it looks like Britney's fleet of engineers (er, the X Factor hair and makeup team) returned him to a less embarrassing state these days.