I'll give you a question, please answer with step-by-step reasoning process.
Passage: Elizabeth Ann Theresa "Betty" Lynn (born August 29, 1926) is a former American actress. She is best known for her role as Thelma Lou, Deputy Barney Fife's girlfriend, on The Andy Griffith Show.\n\nQuestion: Based on this passage, who played thelma lou on the andy griffith show?

Elizabeth Ann Theresa `` Betty '' Lynn
This is the relevant information: She is best known for her role as Thelma Lou, Deputy Barney Fife's girlfriend, on The Andy Griffith Show.

.

So, the answer is Elizabeth Ann Theresa `` Betty '' Lynn