During Saved by the Bell's final season, Kelly and Jessie disappeared from the cast, with newcomer Tori Scott added, causing a bizarre Tori-Saved by the Bell issue. Premiering in August 1989, Saved the Bell was actually a rebirth of the short-lived Good Morning, Miss Bliss, which centered primarily on Hayley Mills' titular teacher. When that project failed to take off, the concept was retooled into what fans would come to know, with only four existing characters — Zack, Screech, Lisa, and Mr. Belding — making the transition over. Saved by the Bell ruled Saturday mornings for the early 1990s. It was also a hit in reruns on cable and in syndication. This led to sequel shows, spinoffs, TV movies, and a revival on Peacock. When people think of Saved by the Bell though, it's likely most don't think of Tori Scott.

https://screenrant.com/saved-by-bell-tori-scott-kelly-jessie-replace/