Updated 10:08 PM ET, Thu May 13, 2021 Melanie Lynskey, Allison Janney and Jaime Pressly in the 'Mom' series finale (Michael Yarish/Warner Bros. Entertainment). The following contains spoilers about the "Mom" series finale. (CNN)The "Mom" finale was as much about beginnings as endings, as the CBS sitcom about sobriety settled for a low-key finish, which included a wedding but not the return of one of its original stars. Anna Faris left the show before the season began, citing a desire to "pursue new opportunities." That left Allison Janney -- the "Mom" of the title in connection with her -- to carry on with the able supporting cast.