Mary

 is a witch who is friends with Bertha and Clara. She is dismayed that Samantha is trying to give up magic.

Mary meets with her friends at Samantha's house to discuss what to do about Halloween. They want to find a way to dispell the ugly stereotypes mortals have about them. When she sees mortal children wearing ugly witch masks, she goes home to cry.

Samantha suggests enlisting Darrin's help to counter these images, but Mary is skeptical, saying mortals do not seem to do anything very well. Samantha persists and convinces Darrin to change the stereotypical images he had originally conceived for his client's Halloween candy to that of a beautiful witch. Darrin runs afoul with Mr. Brinkman, who wants an ugly witch for his product, and is fired.

Mary has sympathy for mortals and feels guilty about Darrin losing his job over the disagreement with Mr. Brinkman. She goes with Bertha, Clara and Samantha to Mr. Brinkman's home to protest these depictions. Samantha turns Mr. Brinkman into an ugly, old hag to teach him a lesson. He repents and Samantha restores him to normal. The witches pop out, leaving him to wonder if it was all a dream.

Trivia
Mary is one of the few witches in the series whose first name does not end in the soft "a" sound.