Probably the most successful American Idol winner up until now would be Jennifer Hudson. She was unknown until she participated on American Idol. She was on the third seasons and became a finalist. She launched her singing career and also her acting career. Her films include Dreamgirls which launched her acting career and singing career from American Idol.
No other winners from American Idol starred in a movie only a year or two after winning American Idol. Hudson also acted in Sex and the City, The Secret Life of Bees, Winnie Mandela, The Three Stooges, Black Nativity, Lullaby, Sing, Sandy Wexler, Monster and Cats, to name a few. She also acted on a few television shows including Empire and Smash.