A.P. Bio is one of the more under-appreciated sitcoms of its era. First premiering on NBC in 2018 before getting the boot over to streaming on Peacock in 2020, the Mike OBrien-created series takes the gruff teacher with a secret heart of gold trope and turns it on its head.The four-season show follows Jack Griffin (played by Its Always Sunnys Glenn Howerton), a disgraced Harvard philosophy professor who is forced to return home to Toledo, Ohio and take a job as an A.P. Biology teacher at Whitlock High School. Jacks heart contains no gold, secret or otherwise. He begins his story an asshole and largely ends it the same way. He also maintains an almost metatextual awareness of his role as a beleaguered-but-redeemable teacher archetype and makes a concerted effort to not allow his class full of lovable, precocious honor students to change him in any way.And yet, A.P. Bio quickly evolves into a warm hang out comedy anyway. Thats largely due to the sheer charisma of the people involved. The shows ensemble is neatly split between the teachers in Jacks world (led by Patton Oswalt as the schools principal and Paula Pell as his loyal secretary) and the students. Casting young actors can be a bit of a crapshoot but the performers that A.P. Bio finds to fill out its titular class all shine and prove to be the perfect accompaniment for Howertons cranky talents.With A.P. Bio now on Netflix for the first time, lets take a moment to take stock of that cast, what they bring to the show, and what theyve been up to since. The TeachersGlenn Howerton as Dr. Jack GriffinA.P. Bio is very much designed as a showcase for TV comedy heavy hitter Glenn Howerton. Prior to (and indeed concurrently with and after) his role as Jack Griffin, Howerton was best known for portraying Dennis Reynolds on long-running FX comedy Its Always Sunny in Philadelphia. Going on two decades, Howertons performances as the borderline sociopathic Dennis has been a comedic masterclass. Now viewers have gotten to know him a little better via The Always Sunny Podcast and his award-winning role as Blackberry co-founder Jim Balsillie in 2023s Blackberry.Lyric Lewis as Stef DuncanStef Duncan is a history teacher at Whitlock High School and part of the unshakeable Stef-Mary-Michelle friendship trio. Playing her is Lyric Lewis, who has previously appeared in TV comedies Baskets, iCarly, and Party Down. Mary Sohn as Mary WagnerMary is an art teacher at Whitlock High School and part of the aforementioned Stef-Mary-Michelle friendship trio. Playing her is Mary Sohn, a comedic actress who has appeared in Miracle Workers, Between Two Ferns: The Movie, and Curb Your Enthusiasm. She has also made several appearances voicing characters on the Comedy Bang! Bang! podcast. Jean Villepiqueas Michelle JonesMichelle Jones is the home economics teacher at Whitlock High School and is the oddball spoke of the Stef-Mary-Michelle friendship trio. Jean Villepique has popped up in numerous comedy series since 2007, including The Office, Modern Family, and Veep. Shortly before A.P. Bio, she voiced adoption caseworker Tracy in BoJack Horseman. Patton Oswaltas Principal Ralph DurbinPrincipal Ralph Durbin is the overmatched leader of Whitlock High School and the closest thing Jack Griffin has to a friend. Playing Durbin is the prolific comedy legend Patton Oswalt, who has been in just, everything. In addition to his long-running career as a standup comic and actor, Oswalt is known to young audiences as the voice of Remy in Pixars Ratatouille. Paula Pellas Helen Henry DemarcusThe perfectly-named Helen Henry Demarcus is Principal Durbins secretary who views him as something resembling her husband, son, best friend, and platonic soulmate. Playing Helen is comedic secret weapon Paula Pell. A respected writer at Saturday Night Live from 1995 through 2020, Pell has moved in front of the camera more in recent years, playing prominent roles in Parks and Recreation, Documentary Now!, and Girls5eva.The StudentsAparna Brielleas Sarika SarkarThe type-A Sarika Sarkar is the student most invested in actually learning A.P. Biology. Poor girl. Before A.P. Bio, Aparna Brielle had small roles in the shows Grimm and The Librarians. Since then shes become a part of Kevin Smiths View Askewniverse with a role in 2019s Jay and Silent Bob Reboot and the upcoming Mallrats sequel. She also appeared in Netflix series Boo, Bitch and FUBAR.Nick Peine as Marcus KasperakMarcus Kasperak is something close to Jack Griffins nemesis and is openly described as his least favorite student. Playing this stick-in-the-mud is Nick Peine who previously appeared in the 2016 comedy Office Christmas Party to go along with guest roles on Shameless, The Middle, and Fresh Off the Boat.Allisyn Snyderas Heather WilmoreThe heavily-bespectacled Heather Wilmore is weirdly loyal to Mr. Griffin and develops an unlikely love interest within her class. Before A.P. Bio, as a child actor, Allisyn Snyder played the role of Zora Lancaster on the Disney Channels Demi Lovato-starring series Sonny with a Chance and its Lovato-less spinoff So Random! She also created the long-running YouTube character Astrid Clover and portrayed her for more than seven years and 350 videos. She has since moved into filmmaking and directed indie horror movie Howdy, Neighbor! in 2023.Eddie Leavy as Anthony LewisAnthony Lewis is perhaps the most beloved student in Griffins A.P. Bio class. Playing the gentle giant is Eddie Leavy, who has also popped up in TV comedies like The Other Two, Tosh.0, and Ryan Hansen Solves Crimes on Television.Jacob Houston as Victor KozlowskiThe soft-spoken Victor is one of the more eminently likable occupants of A.P. Biology class. Playing this very demure Midwesterner is Jacob Houston, who has had guest roles in Criminal Minds and American Vandal. He is also charmingly credited as Smartass for his role as Kevyn Tans right hand man in Yellowjackets. Houstons Instagram handle is @giantloserbaby where his posts occasionally feature his former A.P. Bio castmates.Spence Moore IIas Dan DeckerEvery class has a figure so towering they can only be known as their full name. Dan Decker is such a figure on A.P. Bio. Playing the popular student is Spence Moore II, who came to the role by way of The CWs All American, where he played a similarly athletic character. He also appeared in Netflixs 13 Reasons Why. Since A.P. Bio wrapped, Moore II has played Matteo Mannheim on Superman & Lois and scored a main role as Jacob Nash on NBCs Brilliant Minds. Sari Arambulo as GraceThat the dreamy and ditzy Grace found her way into A.P. Biology underscores the kind of shambling operation that Whitlock High School is under Principal Durbin. Prior to A.P. Bio, Sari Arambulo popped up in guest roles in family shows like Netflixs Alexa & Katie and Disney Channels Girl Meets World. After the show wrapped, she had a four-episode arc as Bella in The L-Word: Generation Q.Marisa Baram as MarissaA relatively late addition to the class in season 1, Marissa becomes a crucial part of the A.P. Bio ensemble. Playing Marissa is another Marisa, albeit with one s fewer. Marissa Baram appeared in two episodes of How to Get Away with Murder before her time on the show. Currently she plays secretary Gail Price on NCIS: Origins.