The Keystone Kops was a series of silent film comedies featuring an incompetent group of policemen produced by Mack Sennett for his Keystone Film Company between 1912 and 1917.

The idea came from Hank Mann , who also played police chief Tehiezel in the first film before being replaced by Ford Sterling . Their first film was Hoffmeyer's Legacy (1912) but their popularity came from the 1913 feature The Bangville Police. However as early as 1914 they were being pushed out by Sennett in favour of comedians like Charlie Chaplin and Roscoe 'Fatty' Arbuckle.

The term has since come to be used to criticize any group for its mistakes, particularly if the mistakes happened after a great deal of energy and activity, or if there was a lack of coordination among the members of the group. For example, in June 2004, the election campaign of the Liberal Party of Canada was compared with "the Keystone Kops running around" by one of its parliamentary members, Carolyn Parrish.

In 1994, the Keystone Kops were honored with their image on a United States postage stamp designed by caricaturist Al Hirschfeld.

The Keystone Kops also appear in the computer game NetHack, typically when the player steals from one of the shops. They are more dangerous than their cinematic inspiration however; they typically surround the player's character so escape is impossible, and then attack with rubber hoses from all directions, while temporarily blinding the player with thrown cream pies.

Movies featuring the Keystone Kops

• Hoffmeyer's Legacy (1912)
• The Bangville Police (1913)
• Barney Oldfield's Race for a Life (1913)
• Mabel's New Hero (1913)
• In the Clutches of the Gang (1914)
• Making a Living (1914)
• The Noise of Bombs (1914)
• Love, Loot and Crash (1915)
• Wished on Mabel (1915)