Frank Sinatra is the only one that went from teen idol to superstar.

10 UK No. Leif also played the role of Leonard Unger the son of Felix Unger (Tony Randall) on the ABC series The Odd Couple a part that previously was played by Willie Aames.

Leif Garrett (born Leif Per Nervik; November 8 1961) is an American singer actor and television personality. He became famous in the late 1970s as a teen idol but received much publicity in later life for his drug abuse and legal troubles.