Big Bird was worried about not seeing Mr. Hooper, then it was explained to him that Mr Hooper had died. The writers, producers and cast of Sesame Street did an extraordinary job IMO explaining death in a gentle but respectful way to Big Bird to help kids understand such a difficult concept as death.
Jean Stapleton left ***All in the Family ***at the end of the 1979-80 season. In the first episode of the 1980-81 season, Archie tries to talk to Edith, and says something like, “Aw, Edith, I was supposed to die first.”
Jack Soo of*** Barney Miller ***died in 1979, and his character, Nick Yemana, “died” too. One of the running gags on that show was that Nick made horrible coffee. In a tribute episode, all the detectives “toast” Yemana with a cup of coffee.