JoAnn Wilson (21 August 1939 – 21 January 1983) was the wife of Canadian politician Colin Thatcher who murdered her after the end of their marriage.
Wilson was born JoAnn Geiger in Osage, Iowa to Harlan and Betty Geiger. She met Colin while attending Iowa State University in 1960, and in 1962 the couple married and relocated to Moose Jaw, Saskatchewan. While Colin was pursuing his political ambitions, JoAnn helped raise their three children and worked variously as a teacher, bookkeeper, and interior designer. The Thatcher marriage began to sour in the late 1970s, culminating in physical abuse and finally a divorce. Colin continued to abuse and harass JoAnn even after her marriage to Tony Wilson on 3 January 1981.
Two years after an unsuccessful attempt on her life, JoAnn was found beaten and shot to death in the garage of her Regina home. After a lengthy police investigation, Thatcher was charged and convicted of the murder.