George Clooney: then
You know them best as movie stars, but all of these Hollywood hotshots had their beginnings on the small screen...
George Clooney first made a splash as gorgeous paediatrician Dr Doug Ross in hit hospital drama ER. The actor served five years on the small screen until he hung up his stethoscope in 1999.
But George didn't forget his roots, and returned to the show for a cameo in the final season.