Sons Jack O'Connor (born 1992) and Declan O'Connor (born 1997) with Pat O'Connor.

Graduated from Oak Park River Forest High School.

Suffered a serious mental and emotional breakdown during the problem-plagued shoot of the James Cameron film The Abyss (1989).

Replaced Robin Wright Penn, due to pregnancy, as Maid Marion in Robin Hood: Prince of Thieves (1991) with Kevin Costner.

Was nominated for Broadway's 2003 Tony Award as Best Actress (Musical) for portraying the Aldonza/Dulcinea character in a revival of "Man of La Mancha."

Of all the people ever to be nominated for an Academy Award for acting, Mastrantonio has the longest name.

Once trained for a career as an opera singer.

Listed as one of twelve "Promising New Actors of 1986" in John Willis' Screen World, Vol. 38.

Italian-American.