Elizabeth Ann Theresa "Betty" Lynn (born August 29, 1926) is a retired American actress.
She is best known for her role as Thelma Lou, Deputy Barney Fife's girlfriend, on The Andy Griffith Show.
During the 1940s and 1950s, she appeared in many films, including Sitting Pretty (1948), June Bride (1948), the original Cheaper by the Dozen (1950) and Meet Me in Las Vegas (1956).