Warning: this article contains SPOILERS for Abbott Elementary season 4, episode 10, “Testing”.Abbott Elementary has become synonymous with its roster of hilarious teachers, but one may be leaving the titular school soon. Despite the sitcom being well into season 4, very few changes have been made to the faces at Abbott Elementary, aside from more characters being added. The cast of Abbott Elementary season 4 includes the same seven main characters the mockumentary has had since its series premiere: Janine (Quinta Brunson), Gregory (Tyler James Williams), Jacob (Chris Perfetti), Barbara (Sheryl Lee Ralph), Melissa (Lisa Ann Walter), Ava (Janelle James), and Mr. Johnson (William Stanford Davis). Losing any would change the show.

https://screenrant.com/abbott-elementary-season-4-episode-10-barbara-exit-set-up-explainer/