Keystone Kops

The Keystone Kops were fictional policemen. They were clumsy and not very well organized. They were in silent comedy movies in the 1910s. The movies were produced by Mack Sennett between 1912 and 1917. Their first movie was "Hoffmeyer's Legacy" in 1912. They became popular from the 1913 short movie "The Bangville Police". 
One of the Keystone Kops movies was "A Thief Catcher", made in 1914. That movie was lost for a long time. In 2010, it was found at an antique sale in Michigan. Charlie Chaplin has a small role in it as a Keystone Kop. Before the movie was found, people didn't know that Charlie Chaplin had played a Keystone Cop.