Mercer continued to voice the one-eyed Sailor for the Fleischers, for Paramount's Famous Studios cartoons (1942–1957), for a series of television cartoons for King Features Syndicate, and for a Saturday morning cartoon show (1978) produced by william Hanna and Joseph Barbera (as well as the lines for the opening segment of the live action movie; the film's regular role of Popeye was played by Robin Williams). Mercer also did other cartoon voices, including all the voices for a series of Felix the Cat cartoons produced in 1959-1960. Mercer also did the voices of Wimpy, Poopdeck Pappy, Popeye's nephews, King Little, Twinkletoes the Carrier Pigeon, and the bumbling spies Sneak, Snoop, and Snitch in Fleischer's Gulliver's Travels, and a number of voices, including Mr. Bumble and Swat (the Fly) for Fleischer's Mister Bug Goes to Town, and the mad scientist in one of the Fleischer Superman cartoons. Mercer's natural voice was relatively high-pitched for a man, and he was able to do some of the female voices as well.