Thelma Lou's Cousin Karen on the Andy Griffith Show was played by Mary Grace Canfield.
Mary Grace Canfield was born in Rochester, New York and is the second child of Hildegard (née Jacobson) and Hubert Canfield.
Mary Grace Canfield grew up in Pittsford, New York and she also had an elder sister, Constance, who was two years older than her.
Mary Grace Canfield died in 2014.