Baker, at 3 feet, 8 inches (112 cm) tall, was a circus and cabaret performer with entertainer Jack Purvis when George Lucas hired him to be the man inside of R2-D2 in Star Wars in 1977. Baker and actor Anthony Daniels, who plays C-3P0 in the films, are the only actors to appear in all five Star Wars films. Baker even played an additional role in 1983's Return of the Jedi, when he played one of the furry Ewoks.
Other films Baker has appeared in include 1980's The Elephant Man, 1981's Time Bandits, 1984's Amadeus and the 1986 Jim Henson film Labyrinth.
In the late 1990s, Baker launched a stand up comedy career.