Ma Barker, also known as Arizona Barker, was a real-life criminal who gained notoriety as the leader of the Barker-Karpis Gang during the early 1930s. She was born in 1873 in Missouri and was married to George Barker, a criminal who was killed during a shootout with the police in 1930.

After her husband's death, Ma Barker and her four sons (Herman, Lloyd, Arthur "Doc", and Fred) formed a gang that carried out a string of robberies and kidnappings throughout the Midwest. They were known for their violent and brutal tactics and were responsible for several deaths, including those of law enforcement officers.

In the movie "Bloody Mama," Shelley Winters portrays Ma Barker as a cold and calculating criminal who uses her sons to carry out her plans. She is depicted as a manipulative and ruthless woman who is willing to do whatever it takes to achieve her goals. The character is shown to be highly intelligent and cunning, using her wit and charm to manipulate others.

Overall, the character of Ma Barker in "Bloody Mama" is a highly fictionalized representation of the real-life criminal. While the movie takes many liberties with the facts, it is still a compelling and intense portrayal of a woman who was once considered one of the most dangerous criminals in the country.