The Secret Origins of the Fantastic Four can be found in the popularity of the Justice League — but also in the Doc Savage pulps:
Doc Savage’s crew consisted of his Fabulous Five — Johnny, Monk, Ham, Renny, and Long Tom — and, later, his (female) cousin Pat. Combining some of these characters and adding superpowers yields the Fantastic Four:
DR. REED RICHARDS is based on DR. CLARK SAVAGE aka Doc Savage. Reed is a brilliant inventor and scientist just like Doc. Reed’s habit of constantly using big words comes from Johnny Littlejohn.BEN GRIMM is based on MONK MAYFAIR. Ben is a “Thing”; Monk resembles a gorilla. Ben’s running feud with Johnny is based on Monk’s squabble with Ham. Like Renny, who was described as “thin and GRIM,” Ben also loves to slam his huge fists through doors — or anything else.
SUSAN STORM is based on PAT SAVAGE, the unofficial sixth member of Doc’s team. The beautiful and glamorous Pat is Doc’s cousin; Susan is Johnny Storm’s sister.
JOHNNY STORM is based on JOHNNY LITTLEJOHN. Johnny gets his name from Littlejohn. Moreover, it was said that “underneath Littlejohn’s gaunt appearance burns a strength and fire unbelievable.”