Possible Clues:

• Mack of movies
• 'Keystone Kops' producer
• Early Chaplin employer
• Mack ___, who created the Keystone Kops
• Producer of the Keystone Cops films
• Rival of Roach in early film comedy
• ''The King of Comedy''
• Big name in slapstick
• Keystone Studios founder Mack
• ''Master of fun'' honorary Oscar winner