Maureen "Mo" O'Toole (born March 24, 1961)[1] is an American water polo player and coach.

O'Toole started playing water polo during the swimming off-season at age thirteen.

At Wilson High School in Long Beach, California she joined boys' water polo because there was no girls' team.

"Mo" (as her teammates called her) was a constant figure on the team from 1978 to 1994, except in 1991 when she gave birth to her daughter Kelly.

She has coached water polo at Rio Hondo College in Whittier, California and at UC Berkeley from 1995 to 1997, and has a master's degree in education.