Marcia Wallace

When Bob Newhart decided to do a sitcom after more than a decade of standup comedy, he had one nagging worry:

Actress Marcia Wallace appeared in scores of TV shows, from The Bob Newhart Show to  Taxi. But Wallace, who died on Oct. 25 at age 70 in Los Angeles, made her biggest impression in The Simpsons , as the voice of Edna Krabappel, an embittered, chain-smoking fourth-grade teacher with the misfortune…