Keystone Cop

The Keystone Cops (often spelled "Keystone Kops") were fictional incompetent policemen, featured in silent film comedies in the early 20th century. The movies were produced by Mack Sennett for his Keystone Film Company between 1912 and 1917.

The idea for the Keystone Cops 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 stemmed from the 1913 short The Bangville Police starring Mabel Normand.

As early as 1914, Sennet shifted the Keystone Cops from starring roles to background ensemble, in support of comedians like Charlie Chaplin and Fatty Arbuckle. The Keystone Cops serve as supporting players for Marie Dressler, Mabel Normand, and Chaplin in the first full-length Sennett comedy feature, Tillie's Punctured Romance (1914), as well as in Mabel's New Hero (1913) with Normand and Arbuckle; Making a Living (1914) with Chaplin in his first screen appearance (pre-Tramp); In the Clutches of the Gang (1914) with Normand, Arbuckle, and Al St. John; and Wished on Mabel (1915) with Arbuckle and Normand, among others. Comedian/actors Chester Conklin, Jimmy Finlayson, Ford Sterling and director Del Lord were also Keystone Cops.

...
Wikipedia