The Cat in The Hat may be the most iconic of Dr. Seuss' characters, aside from, of course, the Grinch. In 1971, DePatie-Freleng took over the license to produce cartoon specials based on Seuss' books, and Cat, it happens, was their first project. Chuck Jones and his staff, including director Hawley Pratt and musical director Dean Elliott, came over from MGM, where they'd produced the first two Seuss specials for CBS, How The Grinch Stole Christmas & Horton Hears a Who!, the latter of which had previously been adapted by Warner Bros. as a short several years earlier.
Humorist Allan Sherman voiced the Cat and also narrated, with Daws Butler lending his voice to the fish. Pamelyn Ferdin (Curiosity Shop) was the voice of Sally, one of the two children. Something got lost in the translation when Mike Myers ("Austin Powers") adapted the story into a feature film some years later and essayed the title role himself in a live-action film.
Universal, by virtue of acquiring the license for live action adaptations of Grinch and the Cat, holds the rights to this classic:
The cartoon hasn't been seen much in recent years, even after the movie was released, which speaks volumes about cablers' lack of interest. The Cat, of course, has since returned in a pair of daily children's shows, the current one airing on PBS and starring Martin Short (ex-SCTV, Saturday Night Live).