The Most Popular Girls in School (abbreviated MPGIS) is an American adult stop-motion animated comedy web series that debuted on YouTube on May 1, 2012. Created by Mark Cope and Carlo Moss, the series animates Barbie, Ken and other fashion dolls, usually with customized costumes and hairstyles, as various characters. MPGIS follows the exploits of a fictional high school cheer leading team in Overland Park, Kansas and their friends, family and enemies. Variety described the series as "Mean Girls meets South Park". The first episode has been viewed over 11 million times, and many episodes have received views in the millions.

In April 2013, MPGIS parodied the viral email rant of Delta Gamma sorority member Rebecca Martinson by having the character Brittnay Matthews (voiced by Lily Vonnegut) reenact the so-called "Deranged Sorority Girl Email". The MPGIS video went viral itself. On May 1, 2018, Extra Credit Studios announced a sixth season to be in development, as well as a Patreon to crowdfund MPGIS in addition to new spin-off shows The Most Popular Girls in Quarantine, Keeping Up With The Van Burens, and Models.