Before the were stars

What movies or TV programs did actors appear in before they became stars?

Leonard Nimoy, Fess Parker, and Clint Eastwood we all in the movie THEM!.

Nimoy played an AF NCO, Fess Parker was the pilot in the loony ward, and Eastwood was a pilot in the jet although the oxygen mask hid his face.

Leonard Nimoy later went on top play Mr. Spock in Star Trek, Fess Parker played Dave Crockett in two Disney movies and Daniel Boone on TV, and Clint Eastwood played Rowdy Yates on Rawhide and then went on to stardom in Italian westerns and then American movies as an actor and director.

What actors have you seen in their early roles.