Louis Francis Cristillo aka Lou Costello (March 6, 1906 - March 3, 1959) is an American actor, producer and comedian from Paterson, New Jersey.

Costello is best known as half of the comedy team of Abbott and Costello, with Bud Abbott.

Costello worked as a carpenter at MGM and Warner Brothers after high school. After that, he worked temporarily as a stuntman, and then eventually became vaudeville comedian.

In 1931, while performing in Brooklyn, New York, Costello's straightman became ill and the theater cashier, Bud Abbott, filled in.

Throughout the 1930s, Abbott and Costello began performing together in burlesque shows, minstrel shows, vaudeville and movie houses.

At Costello's request, all profits earned from the act were split 60/40, favoring Abbott, because, according to Costello, "comics are a dime a dozen. Good straight men are hard to find."

In 1938 they received national exposure for the first time by performing on the Kate Smith Hour radio show, which lead to the duo signing with Universal the following year. Abbot and Costello released their first film in 1940 entitled, One Night in the Tropics. Although Abbott and Costello were only filling supporting roles in the film, they stole the film with their classic routing Who's On First. (Abbott and Costello are the only two non-baseball players honored in the Baseball Hall of Fame museum in Cooperstown, New York, because of their legendary Who's On First routine.)

Within a couple of years, the comedy team had also their own television and radio shows.

Abbott and Costello split up in 1957, after troubles with the Internal Revenue Service that left both men broke.

Costello died in 1959 from a heart attack and was interred in the Calvary Cemetery in East Los Angeles, California.