Louis Francis Cristillo (March 6, 1906 – March 3, 1959), professionally known as Lou Costello, was an American actor, best known for his film comedy double act with straight man Bud Abbott and their comedy routine "Who's on First?" The comedians, who teamed up in burlesque in 1936, were among the most popular and highest-paid entertainers in the world during World War II. In 1942 during a national tour they sold $85 million in war bonds in 35 days. By 1955 their popularity waned due to overexposure and their film and television contracts lapsed. The partnership ended soon afterwards.