Kate Barker, better known as Ma Barker, was the mother of several American criminals who ran the Barker–Karpis Gang during the "public enemy era" when the exploits of gangs of criminals in the Midwestern United States gripped the American people and press. She traveled with her sons during their criminal careers.

The Barker–Karpis Gang was one of the longest-lived criminal gangs during the Depression Era, spanning from 1931 to 1935. The gang was founded by Fred Barker and Alvin Karpis, and later joined by Fred's brother Arthur "Doc" Barker. Along with the three core members, the gang's network spanned up to 25 members at one point.