Moira was born on the sixth day of March in 1968. She is the third child in a family of six children. Her parents, both of great talents, were Irish immigrants. (Her mother, Anne is a nurse, and her father was trained as a concert pianist.) As a child, Moira was raised in Ronkonkoma, New York. She went to Connetquot Senior High School and graduated in 1986.
Moira attended Marymount Manhattan College.
While in high school, Moira was in the play "Annie" (1984). Due to illness, the girl playing a main character was replaced. That replacement caused several cast changes, allowing Moira to play the role of Grace Farrell. She was called 'a great success', thus her career path became clear to her. She wanted to be an actress.
Asides from Heroes, Moira Kelly has been in a plethora of other things such as: 'Two Tickets to Paradise', 'One tree Hill', 'Henry Hill', 'Remember the Daze' and others.
- Moira was listed as one of twelve "Promising New Actors of 1992" in John Willis' Screen World, Vol. 44.
- When cast in David Lynch's Twin Peaks: Fire Walk with Me (1992), Moira went home to get permission from her priest to do her first sexual scene on film.
- Moira narrated the audio book for "Jacob have I loved".
- She was originally cast as Kit Keller in A League of Their Own but an ankle injury on the set of The Cutting Edge prevented that and the role of Kit was given to Lori Petty.
- Moira has two kids by her husband, a Texan businessman. Her daughter, Ella was born in 2001 and her son Eamon who was born in 2003.