Whitman Mayo as Grandpa would speak directly to the camera (as if to the child viewer) with such love and compassion, you wanted him to be your grandpa.
That's Cat! meant, Cool! on the show.
The show's theme song ("That's Cat") was sung by John Sebastian, who also sang the theme song to the 1970s TV show Welcome Back Kotter, and his son, who echoed the words "That's Cat", during the repeated chorus.
That's Cat was created by Executive Producer Giovanna Nigro-Chacon who wrote the weekly feature "Grandpa". Ms. Nigro-Chacon also wrote and produced the only special in the series - the hour-long "That's Cat Christmas". She received a Los Angeles Area Emmy Award nomination for her work.
That's Cat was a children's television show that premiered on Saturday, September 18, 1976. It was both produced by and aired on KNBC, the NBC owned and operated (O&O) station in Los Angeles, California; it was also syndicated to selected NBC O&O stations.