Lacey Chabert voiced Meg Griffin on Family Guy for the show's first season, so did she decide to leave the show? While Family Guy would eventually attract a huge fanbase, the show struggled during its early years. The series was created by Seth MacFarlane (The Orville), who also voices Peter Griffin, the dimwitted title character. Peter can be insanely obnoxious, petty, and rude - in addition to hilarious - and the show follows him and his family, including wife Lois and their three children, Meg, Chris and evil genius Stewie.
While Family Guy had a cult following during its early seasons, lukewarm ratings led to it being canceled in 2002. Thankfully, due to word of mouth the show's popularity increased over time, leading to robust DVD sales. This led it being revived in 2005 and the series has been running ever since. The show's blend of surreal humor, celebrity guest stars, and gross-out gags has proven to be a solid formula, though some fans feel that, like The Simpsons, the show's heyday may have passed.
Mila Kunis (The Spy Who Dumped Me) voices Meg Griffin on Family Guy, having joined the show during season 2. Meg is often on the receiving end of cruel jokes and bullying from her family, which only seems to get worse with each passing season. Kunis is technically the third actress to voice the character. Cree Summer (Voltron: Legendary Defender) was originally cast in season 1 and began recording work, but was later replaced, with Lacey Chabert (Mean Girls) taking over Meg for the first season. Following Chabert's departure from Family Guy, Kunis inherited the role, starting from the third episode of season 2, "Da Boom."
When it comes to the reasons Lacey Chabert departed the series, there's no real drama involved. Chabert was still in school when she worked on Family Guy season 1, so between studying and shooting TV series Party Of Five, she decided to drop out of Family Guy to focus her attention elsewhere. Seth MacFarlane has also confirmed there was no tension and her exit was completely amicable. Strangely, a contractual quirk meant she wasn't credited on the show during its initial run, which may also have been a deciding factor.
Given the meta nature of Family Guy, Meg's replacement has joked about more than once, like when Brian and Stewie travel back in the time to the very first episode in season 10's "Back To The Pilot," where Lacey Chabert's voice is still used for Meg. Kunis is so closely associated with Meg Griffin now its hard to imagine another actress in the role, though Chabert still did a great job with the character.