Betty Johnson is a non-canonical character created for the Agatha Christie's Marple adaptation of the novel By the Pricking of My Thumbs. She and her husband Eric manage the village post office and shop in the village of Farrell St Edmund, where most of the action in the later part of the story takes place. Her involvement in the plot has to do mainly with a clue than Miss Marple and Tuppence Beresford are following: that it was one "Mrs Johnson" who came to take Mrs Lancaster away from Sunny Ridge. See the article for Eric Johnson for details.
Betty Johnson is portrayed by Bonnie Langford.