Thelma Lou, or Thel by boyfriend Barney Fife, is a character on the American television sitcom The Andy Griffith Show (1960-1968).

In another episode, she is mentioned to have attended Mayberry Union High, graduating in the same class with Barney and Andy Taylor.

She is apparently self-sufficient; her occupation is never revealed despite references to a never-seen "office", yet she lives in a roomy and well-decorated house of her own.

"[1] Prior to the arrival of Helen Crump in Mayberry, Lydia Crosswaithe is introduced as one of Thelma Lou's friends.

Lydia's extremely odd personality doomed an effort by Barney and "Thel" to arrange a date and possible romantic match with Andy.

Barney dates other women besides Thelma Lou (mainly, diner waitress Juanita, who is mentioned, but never seen or heard).

The two broke up in one episode when Barney pays a bit too much attention to an attractive newcomer to Mayberry.

Intent on getting back with Thelma Lou, Barney discovers she has been married six weeks to a man named Gerald Whitfield.