Overland Park High School is the main setting of "The Most Popular Girls In School" and is home to most of the main characters. Overland Park High School is shown to have a complex social food chain that is primarily led by the cheer team and the football team. Principal Nubbins is the current principal of Overland Park High School.
- Ashley Katchadorian
- Amberlynn Weggers
- Brittnay Matthews
- Connor Devarnan
- Jonathan Getslinhaumer
- Judith Dinsmore
- Justin Michaelson
- Jenna Dapananian
- Jennifer McMinnimen
- Mackenzie Zales
- Matthew Derringer
- Rachel Tice
- Saison Margeurite
- Shay Van Buren
- Steven Carmichael
- Tanner Christiansen
- Trisha Cappelletti
- Trisha 2
- Amber Zendejas - Mentioned in Episode 3 when Trisha throws up and says, "remind me to text Amber Zendejas" so she can clean up the bathroom.
- Ira Martinez - Allegedly a freshman Trisha makes out with behind the popcorn stand, according to Mikayla Van Buren.
- Chris A. Peterson - Running for AX club president, as seen on a poster behind Trisha in Episode 14.
- Jessica Taylor - Also named on a poster representing her campaign for treasurer behind Trisha in Episode 14.
- Kay Proctor - Running for Class President, as seen on a poster behind Brittnay in Episode 16
- Tim Wallace - Briefly mentioned by Trisha in Episode 6. Owns a new Fiat.
- Megan Rankin - A freshman running for freshman class president, as seen on a poster behind Lunch Lady Belinda in Episode 19.
- Tom Rotolo - A student running for Chemistry Club president, also on a poster behind Lunch Lady Belinda in Episode 19.
- Ray Oresco - A student running for Class President, on a poster behind Mackenzie and Trisha in Episodes 36 and 53.
- Isabel Chambers - A student suggested by Mackenzie to join the cheer squad in episode 36. She apparently chews taffy in class.
- Bailey Farhar - A student suggested by Trisha to join the cheer squad in episode 36. She is described as blonde.
- Overland Park Cheer Squad - Head Cheerleader Mackenzie Zales
- Overland Park Football Team - Quarterback Tanner Christiansen
- Overland Park Student Collective - run by Jenna Darabond and Jenna Dapananian
- Prom Committee
- Chemistry Club
- AV Club - Rachel Tice and Judith appear to be the only members.
- Book Club - Deandra was briefly a member before joining the football team.
- Cameron Van Buren
- Jayna Van Buren
- Blake Jensen
- Taylor McDevitt
- Bridget Tice
- Ruth Van Buren
- Trish Cappelletti
- Jenna Darabond
- Lunch Lady Belinda
- Principal Nubbins
- Coach Spitz
- Desmond Irie
- Mr. Reynoso - Chemistry teacher
- John Michael McNeely
- Ms. Bottomon - English teacher
- Overland Park High School itself is not an actual high school in Kansas. However, there is an actual city called Overland Park in Kansas (in fact, it's the second largest city in the state) and there's also an actual Blue Valley School District, Blue Valley Northwest High School and Atchison High School.
- The school building used in MPGIS is the exterior of Wausau East High School in Wausau, Wisconsin.
- Their school mascot is a bear, though it is referred to as "Grizzly".
- Their school colors are red and white.