In which TV series is A.C. Slater a main character?

Who played Newman in 'Seinfeld'? In which TV series is Newman a main character? Who played Zack Morris in 'Saved by the Bell'? Who played A.C. Slater in 'Saved by the Bell'? Who played Kelly Kapowski in 'Saved by the Bell'? In which TV series is Kelly Kapowski a main character? Who played Screech Powers in 'Saved by the Bell'? In which TV series is Screech Powers a main character?