In 1985, my partner, David and I created a comeback show for Mary Tyler Moore called (oddly enough) MARY. We were extremely fortunate to have a great casting director in Molly Lopata. All summer we spent auditioning actors for the series. Most you've heard of. Some even big names.
One day Molly brought in a newcomer to read for the role of Jo Tucker, Mary's acerbic workmate. We loved her. She was funny, real, and so fresh. A definite call-back.
Eventually we had to go to CBS to get cast approval. They asked to see two candidates for each role. For the part of Jo we brought in Kathy Bates and this newcomer. Both were wonderful. CBS was thrilled with either pick. We decided to go with the newbie. There was just something very special about Katey Sagal.
Here is a sample of her work on MARY. I don't know who put this together but many thanks. It not not only shows her comedic side but her singing ability too.