Meg Griffin is the daughter of Peter and Lois Griffin. She is the eldest child and older sister to Chris and Stewie Griffin.
In the original pilot she was voiced by Rachel McFarland. When the series got picked up Meg was voiced by Lacey Chabert, but after the first production season, Chabert left the show due to a combination of her school work and role on "Party of Five".
Meg is currently voiced by Mila Kunis but for the episode "Don't Make Me Over" where Meg sings, her singing voice is provided by Tara Strong.
For the bonus material in Stewie Griffin: The Untold Story, Ali Hillis provided the singing voice for Meg in the segment where the character sang for the troops (making them run away in horror).