Megan "Meg" Griffin is a fictional character from the American animated television series Family Guy. She first appeared in the show's pilot episode, "Death Has a Shadow", on January 31, 1999. She was originally voiced by Lacey Chabert; however, she has been voiced by Mila Kunis since the show's second season. Writer Seth MacFarlane created and designed Meg after his 1995 student film, The Life of Larry, was picked up by 20th Century Fox for a series order. Meg is the eldest child and only daughter of Peter and Lois Griffin and the sister of Chris and Stewie. A social outcast, Meg is typically depicted as being mistreated and neglected by her family, though this has been downplayed in later seasons. Despite this, she is shown to be extremely talented and resourceful, having a kinder personality compared to the rest of her family.

Similar to Lois, Meg has gone through numerous personality changes since the debut of the show in 1999. In early seasons, she was portrayed as a self-conscious and insecure adolescent. She is treated unfairly and abused by various people and has numerous insecurities that prompt her to try to be part of the "in-crowd". However, this only results in her getting rebuffed by the many bullies of this circle, particularly Connie D'Amico, the head cheerleader of the local high school, James Woods Regional High School. In contrast to this, a nerdy Jewish student named Neil Goldman is attracted to her, to her dismay.

While Meg is usually a pushover, she can get angry when pushed too far, though such occasions are usually rare. This can be seen in the episode "Seahorse Seashell Party", where she strongly insults and defames Peter, Lois, and even Chris for their inconsiderate actions toward her. In the episode "Road to Rupert", Meg assaults a man for insulting her after a fender-bender, and in "The Chicken or the Meg", she decapitates Ernie the Giant Chicken's head after a heated argument. In later seasons, she is shown to be very snarky and deliberately unpredictable towards others, such as in "The Marrying Kind", where she tells off Lois after the latter seeks validation for her jokes. Later seasons exaggerate her uncouth behavior and completely disregard her punching-bag status.

Despite her persistent mistreatment, Meg has proven a variety of times throughout the series that she is more talented and has greater potential than most people bother to realize, such as bird calls, playing the saxophone, speaking and singing in foreign languages, and even sports such as bowling, field hockey, basketball, roller derby, and even Olympic sports. However, her parents are unaware of her talents, oftentimes being completely surprised at her apparent skills.

Many of the show's storylines about Meg involve her trying to improve her life, finding a boyfriend, and reaching breaking points with her family and others who victimize her. She often becomes obsessed with men who show any kindness or affection to her, including the Griffins' friend and neighbor Joe Swanson in the episode "The Hand That Rocks the Wheelchair", and Brian in "Barely Legal". In addition to this, she has been shown to have suicidal tendencies, which has been exacerbated by the abuse she suffers at the hands of her parents.

On the season 1 DVD commentary for the Drawn Together episode "Hot Tub", Cree Summer claims she was offered the role to play Meg but was dismissed by the producers. Meg was voiced by an uncredited Lacey Chabert for the first season, and by Mila Kunis in subsequent seasons after Chabert became busy with school and her role on Party of Five, although some of her work became second season episodes due to production order. Mila Kunis won the role after a series of auditions and callbacks where she was asked to speak more slowly and enunciate more; she was ultimately hired despite being unsure she understood what was expected of her. MacFarlane felt that Kunis invigorated the character, and that her work on That '70s Show showed she could command a scene. MacFarlane stated that Kunis "had a very natural quality to Meg" and she's "in a lot of ways [...] almost more right for the character". Kunis' voice is first heard as Meg in Episode 3 of season two "Da Boom", and the voices switch back and forth in the broadcast order until settling on Kunis. Tara Strong provides Meg's singing voice in "Don't Make Me Over". Archival recordings of Lacey Chabert's voice that she provided as Meg Griffin are used in the tenth season episode "Back to the Pilot" in which Brian and Stewie go back in time to the events of "Death Has a Shadow". However, Chabert does in fact return for the eleventh season episode "Yug Ylimaf" as Stewie references the fact that time has reversed so much that Meg's voice has reverted back from that of Kunis' to Chabert's.

In the first three seasons of the show, Meg was portrayed with a more whiny and uptight personality who was often embarrassed by the family’s acts of bumbling and stupidity, though they cared for her and meant well. In the post-cancellation seasons, this began to change as the inadvertent embarrassment became deliberate bullying and disrespect. Additionally, the show started to flesh out the characters to the point where most of the population of Quahog who knows her, or even just meets her, picks on or disdains her for no reason other than her simply being "Meg".

Meg is depicted as being unpopular in high school due to both her plain appearance and personality. She desperately tries to be part of the cool crowd, but is usually coldly rebuffed. Because of her eagerness for acceptance, she has been recruited "unknowingly" into a suicidal religious cult, and later recruited again unwittingly into her school's Lesbian Alliance (in the episode "Brian Sings and Swings" ). However, Meg does have a moderate number of friends, the best of whom being a group of girls who are often seen with her during occasions such as her slumber parties and gossiping about boys. In later episodes, these girls, known by the names Beth, Patty, Collette, Esther, and Ruth, are characterized as being highly unpopular and dateless, much like Meg.