Played by actress Nicholle Tom.
Margaret is the eldest daughter of Maxwell Sheffield (Charles Shaughnessy) and Sara Sheffield (Bess Armstrong). At first, she felt shy and awkward, and despaired that no boy would ever fall for her. She was forever bickering with her brother, Brighton Sheffield, who felt that she was a nerd. She thought of him as a troll. Her relationship with her youngest sister, Gracie Sheffield was one as a mentor. Maggie gained two more siblings when the twins Eve Sheffield and Jonah Sheffield were born in the final season of the show.
Then, Fran Fine (Fran Drescher) was hired as the new nanny. Fran and Maggie bonded almost instantly and had a close relationship. Under Fran's patient tutelage, she blossomed from a shy and awkward teenager to a very beautiful young woman. In her father's eyes, she is every bit as beautiful as her mother was.
In school, she and Fran had discovered that her gym coach was the same coach that had tormented Fran when she was Maggie's age. Maggie knew her as Coach Stone, but Fran knew her better as Ms. Wickavich. Ms. Wickavich was a bully, who had no liking for either Maggie or Fran, and tormented and taunted both until she choked on her whistle, whereupon Fran, her former student, saving her life. She grudgingly passed Maggie in Gym.
Her father tended to smother her way too much, discouraging her from any kind of activities with boys. It was the "Daddy's little girl" syndrome. He wanted her to remain his little girl, and he couldn't stand it that she was growing up.
When Fran and her father married, Maggie was one of her maids-of-honor. She bonded well, even before the marriage, to Fran's mother, Maggie's soon-to-be grandmother, Sylvia Fine and her soon-to-be great-grandmother, Yetta Rosenberg.
Eventually, Maggie met and married a Jewish underwear model named Michael (Andrew Levitas), who was related, by marriage to Barbra Streisand (his cousin was James Brolin, Ms. Streisand's husband). This made Maggie the only one of the three Sheffield children to get married during the show's run. At the pre-ceremony (with guests of honor being Ms. Streisand and her husband), Fran experienced premature labor pains, and had to go to the hospital. Then Fran snuck out of the hospital, just as Maxwell had everyone else come to the hospital to see Fran, including Barbra Streisand. Dismayed by the failure of her plan, Fran sobbed over the phone. Maggie's wedding was postponed to the next day. In the final episode, Maggie and her husband moved to Europe, where he had a modeling shoot in Venice, but she stayed in Paris with Brighton.
- In Fran Drescher's first book, Enter Whining, Fran explained that Maggie was added later, at the suggestion of a network exec, and wasn't part of the original family, but was said that a shy teenager would be a funny contrast to a brazen and flashy Fran, hence the addition of Maggie.
- Maggie and Michael have a joint wedding ceremony.
- Maggie dyed her hair reddish orange briefly, because Niles talked/tricked her into going back to blonde.
- She is easy to be manipulated by Grace and Niles.
- Maggie had at least 6 boyfriends before dating Michael.
- During her teen years she tried her hand at being a model.
- Many of her interactions with Fran involve Maggie's interest or involvement with a boy.
- She had an adversarial relationship with her brother when they were younger, constantly bickering and arguing.
- Her father claims she bears a striking resemblance to her mother.
- Maggie is already attending college on the field of philosophy in season 5 (episode "Educating Fran"), and assuming it was her first year, she must been around 18-19 during that season, and therefore 19-20 during season 6. However, her age was frequently changed over the course of the series; Maggie was supposed to be 15-16 in season 2, so there she should have her 16th birthday, but she had them in season 3 instead (episode "A Fine Family Feud"), and by the end of season 6, where she should be 19-20, she said she already turned 21 (episode "I'm Pregnant").
- Is one month older than husband Michael.