Agnes Moorehead was in the very first episode of CBSRMT. She also had a long history in radio - The Shadow, Mercury Theater, Cavalcade of America, Suspense, and an episode of Mystery in the Air with Peter Lorre - I'm sure there are probably more shows that she appeared on.   She was only on 2 episodes of CBSRMT. She passed away in 1974, so the two episodes were probably the last things she did.