The Marx Brothers were an American family comedy act that was successful in vaudeville, on Broadway, and in motion pictures from 1905 to 1949. Five of the Marx Brothers' thirteen feature films were selected by the American Film Institute (AFI) as among the top 100 comedy films, with two of them, Duck Soup (1933) and A Night at the Opera (1935), in the top fifteen. They are widely considered by critics, scholars and fans to be among the greatest and most influential comedians of the 20th century. The brothers were included in AFI's 100 Years... 100 Stars list of the 25 greatest male stars of Classical Hollywood cinema, the only performers to be included collectively.

The brothers are almost universally known by their stage names: Chico, Harpo, Groucho, Gummo, and Zeppo. There was a sixth brother, the firstborn, named Manfred (Mannie), who died in infancy; Zeppo was given the middle name Manfred in his memory.

The core of the act was the three elder brothers: Chico, Harpo, and Groucho, each of whom developed a highly distinctive stage persona. After the group essentially disbanded in 1950, Groucho went on to a successful second career in television, while Harpo and Chico appeared less prominently. The two younger brothers, Gummo and Zeppo, never developed their stage characters to the same extent as the elder three. Both left the act to pursue business careers at which they were successful, and for a time ran a large theatrical agency through which they represented their brothers and others. Gummo was not in any of the movies; Zeppo appeared in the first five films in relatively straight (non-comedic) roles. The early performing lives of the brothers owed much to their mother, Minnie Marx (the sister of vaudeville comic Al Shean), who acted as their manager until her death in 1929.