2. Neil Patrick Harris
Known For: Neil Patrick Harris' first big role was as a child, playing Doogie Howser M.D., the teenage physician that helped foster a squeaky clean image for the actor.
The Parody: His appearance in the first Harold and Kumar movie satirised the nature of many child stars who go off the rails, with Harris playing a fictionalised version of himself who is addicted to drink, drugs and hookers. Even with the revelation that Harris is gay, the third film opted to incorporate this into its story, suggesting that Harris' homosexuality is merely a ruse in order to trick women into letting their guard down, allowing him to score more often. It's hilarious because Harris plays the part so well - and with absolute self-awareness - something that's also true of his staggeringly convincing portrayal of heterosexual misogynist Barney Stinson in How I Met Your Mother.