Margot is the senior partner at Will's firm, who starts supervising after Ben Doucette retires and Mr. Stein is sent back to the mental institution. She is stoic and outspoken and has a tendency to casually insult her employees, even outwardly stealing from them, claiming them as gifts. 
She is married to Leonard, whom she admits she does not love anymore; she mentions to Grace that she is having an affair with another man. Margot also mentions having a sister who was murdered. During a dinner at her house, she recalls attending an all-girls school, where she had "half a dozen character-building, lesbian experiences".
When she is first introduced, Will tries to impress her at a dinner party because he is up for a promotion. She later appears when she hires Grace to design the firm, requesting a "tasteful bloodbath" theme.
- Margot mentions having "character-building" lesbian experiences at an all-girls school. In real life, Lily Tomlin is openly gay.
- She is implied to belong to a "secret club downtown" which recruits young girls.
Well, you're not going to be partner. And this has nothing to do with those silly studies that say a mother is less productive in the workplace. But there are a lot of those studies, and they all say the same thing. — firing Roz, Partners
Oh, grow up, Gary. Will's getting promoted because his performance reviews were better. This has nothing to do with your uninteresting wife. — Partners
Hector, I've only got five minutes before I have to get back to the office. I want what I had yesterday. I don't remember what it was, and you weren't working, but I want it anyway. — to a barista, Forbidden Fruit
You remind me so much of my sister. They never found her killer. — to Grace, Forbidden Fruit