4. Tom Hanson (21 Jump Street)
You must be familiar with Jeff Yagher, the star of 80s teenage police series 21 Jump Street who later went on to achieve worldwide fame with his appearances in Tim Burton films and the Pirates of the Caribbean franchise, becoming the highest-paid actor in the world in the process. No? That will be because of the fact that, after filming one episode of the Fox crime drama, Yagher was replaced by a young actor called Johnny Depp, whose screen credits before the series 1987 premiere were limited to bit parts in a Nightmare On Elm Street, Platoon and two much more forgettable films. Yaghers career, meanwhile, has consisted almost solely of one-episode appearances in a host of television shows whilst 21 Jump Street has recently rose to prominence once more due to the release of Channing Tatum and Jonah Hills comedic take on the source material.