Selby was a character actress who played minor roles for the most part – usually a town gossip, maiden aunt, or teacher.

Beginning her career as a radio actress, she made her screen debut voicing one of the elephants in Disney's Dumbo (1941).

She was best known for her recurring role as Ma Smalley, the owner of a boarding house on TV's Gunsmoke (1955).

[1] She had recurring roles on The George Burns and Gracie Allen Show, initially as Gracie's friend Mamie Kelly, and then a recurring role as Lucille Vanderlip the society hostess wife of banker Chester Vanderlip.

[3] Selby was an actress, known for Tower of London (1962), Beyond the Forest (1949) and a recurring role as Aunt Gertrude in The Mickey Mouse Club television series The Hardy Boys: The Mystery of the Applegate Treasure (1956).