One of the great Hanna-Barbara cartoon series of the 1960's was Frankenstein, Jr. and The Impossibles. The Impossibles, ostensably a trio of rock musicians, were, naturally, the alter egos of three superheroes of a most unusual nature. Debuting in 1966, the series cashed in on popular musicians like the Beatles and crimefighters like Batman. Inexplicably, it lasted just the one season but featured voice work by Ted Cassidy, Hal Smith, Don Messick, and others whom you probably know.