Hiram Mankin started working for Jerry Siegel when he was only fifteen years old. While attending the Cleveland High School, he inked 'Superman' stories at night. Due to animosity in the studios, Mankin left after only one month. In 1942, he assisted Zack Mosley on the 'Smilin' Jack' comic for the Chicago Tribune-New York News Syndicate. he also assisted on 'American Adventure for Lafave Newspaper Features (1949-50). He inked an lettered the 'Bugs Bunny' daily (1950-51) and assisted on 'Ditty Dripple', 'Bringing Up Father' and 'Buz Sawyer'. Between 1953 and 1958 he illustrated the 'Roy Rogers' newspaper comic for King Features.
In the 1950s, Mankin did art on National/DC features like 'Gang Busters' and 'Professor Brainstorm'. He also worked on Dell's western comics, like 'Dale Evens', 'Gene Autry', 'Rex Allen' and 'Wild Bill Elliot'. Mankin was furthermore present at Lev Gleason with crime features and 'Daredevil' and in Western's Hanna-Barbera features. In the 1960s he worked as a storyboarder and layout artist for 'Jonny Quest' and industrial films.