Cassius Marcellus Coolidge (September 18, 1844 – January 13, 1934) was an American artist, mainly known for his series of portraits Dogs Playing Poker.

Between 1868 and 1872 he worked as a druggist and sign painter, founded a bank and a newspaper, then moved from Antwerp, New York, to Rochester, where he started painting dogs in human situations.

[2] Coolidge began his art career in his twenties, one of his early jobs being the artist of cartoons for a local newspaper.

He is credited[3] with creating "comic foregrounds," novelty photographs which combined a portrait of the sitter with a caricatured body, produced by the sitter holding between two sticks a canvas on which Coolidge drew or painted the caricature, which he patented.

[4] The final product was similar to the photographs produced using photo stand-ins at midways and carnivals where people place their heads into openings in life-size caricatures.