Kate 'Ma' Barker (Birth name Arizona Clark) ( c. 1871 - January 16, 1935) is a legendary American figure from the 1930s public enemy era , when the exploits of gangs of criminals in the Midwest gripped the American people and press. Today her name is usually mentioned last when people cite the criminals of this period, often after Bonnie and Clyde and John Dillinger. The era led to the creation of the modern FBI.

The actual degree of Barker's own criminality is of some doubt. Though her children were undoubtedly criminals and their Barker-Karpis Gang committed a spree of robberies, kidnappings and other crimes between 1931 and 1935, it appears that the popular image of her as the gang's leader and its criminal mastermind is a myth.

Though she must have known of the gang's activities and it seems clear that she did help them before and after they committed their crimes, there is no evidence that she was ever an active participant in any of the crimes themselves or that she was involved at any level in planning them. Indeed Alvin Karpis, the gang's second most notorious member (though he should probably be its first as he is historically a much more important figure ), later said that:

"The most ridiculous story in the annals of crime is that Ma Barker was the mastermind behind the Karpis-Barker gang ... She wasn't a leader of criminals or even a criminal herself. There is not one police photograph of her or set of fingerprints taken while she was alive ... she knew we were criminals but her participation in our careers was limited to one function: when we traveled together, we moved as a mother and her sons. What could look more innocent?"

Many, including Karpis, have suggested that the myth was encouraged by J. Edgar Hoover and his fledgling FBI to justify his agency's killing of an old lady. She was shot dead when the FBI raided the cottage she was renting with her son Fred at Lake Weir in the Ocala region of Florida on January 16, 1935. It was Fred, who was also killed in the raid, that had been the Bureau's main target.

The myth of Ma Barker inspired a 1970 low budget film called Bloody Mama. Directed by Roger Corman and starring Shelley Winters as Ma, the movie depicts Barker as a corrupt mother who encourages and organises her children's criminality and is notable for an early appearance by a young Robert De Niro playing the part of Lloyd Barker.

The story is also probably the inspiration for the 1977 Boney M music single Ma Baker, the Ma Dalton character in the Lucky Luke series of comic strips and the Beagle Boys characters in the Scrooge McDuck universe.

The pirate chief and her sons in Laputa - The Castle in the Sky movie also may have a connection with this.