Hanks was active in comics from a period of 1939 to 1941 (though as early as 1911 he described himself as a cartoonist), writing and drawing stories for Fiction House and Fox Features Syndicate. His creations include Stardust the Super Wizard, Tabu the Wizard of the Jungle, and Fantomah (one of the first female superheroes, predating Wonder Woman).

A cult following has developed around Hanks' work in recent years. His stories and art have been reprinted in the comics anthology Raw, on the dust jacket of Men of Tomorrow: Geeks, Gangsters, and the Birth of the Comic Book (2004 ISBN 978-0465036578) and in the books Art Out Of Time (2006 ISBN 0810958384) and Supermen!: The First Wave Of Comic Book Heroes 1939-1941 (2009 ISBN 1560979712), and is the subject of the book I Shall Destroy All The Civilized Planets: The Fantastic Comics Of Fletcher Hanks (2007, ISBN 1560978392) from Fantagraphics edited by Paul Karasik. A second volume You Shall Die by Your Own Evil Creation! (June 2009, ISBN 1606991604) reprints the rest of his works.

Hanks was the son of William Hanks, a minister, and Alice Fletcher Hanks, the daughter of English immigrants ... his parents married c.1885. Fletcher himself married Margaret c.1912. Little is known of Hanks's life outside comics; the main source being an interview by Paul Karasik with Fletcher Hanks Junior c.2006. According to his son, Hanks was an abusive father and spouse, as well as being an alcoholic. Hanks earned some income by drawing murals in the homes of the rich and allegedly abandoned his family around 1930 (the U.S. census return for that year shows him described as an artist, living with his wife, Margaret, widowed father, William, and his children Douglas, Alma, Fletcher Jr, and William). He died in February 1976; his frozen body was found by police on a park bench in New York City.