Margaret Mullin was a Human woman who lived during the 22nd century.

In the 2130s, Mullin was in a relationship with Jonathan Archer while he was attending Earth Starfleet Flight School in San Francisco. The day after his graduation in 2136, the 24-year-old Archer proposed to Mullin. However, she turned him down as she did not want to become a "Starfleet widow." (ENT episode: "Twilight")