Colonel John "Renny" Renwick was a world-class engineer, and one of Doc Savage's Fabulous Five Assistants. Philip José Farmer notes in Doc Savage: His Apocalyptic Life that Renny was the early member of the group, Doc aside, to have been wealthy in his own right, but by the end of the pulp series his fortune appears to have run out.
According to Wold Newton scholar Brad Mengel, he was born in 1890, the son of Wold Newton Family member Colina Drummond by her second marriage (her first marriage having produced Richard Hannay in 1877). Alternatively, Savageologist Arthur C. Sippo considers that Renny must have been born in 1882 to have achieved the excellent reputation as an engineer he had even prior to the First World War. These two theories are not entirely incompatible, if a little juggling of dates is allowed (and there is some precedent here - although Richard Hanny's parentage was settled by Farmer in Doc Savage: His Apocalyptic Life, Farmer gave his date of birth as 1874).
Researcher Kevin Breen has stated that Renny married a Chinese woman late in life, and that Sydney Fox from Relic Hunter is their daughter; however, several Wold Newton articles state passim that Sydney is Renny's paternal granddaughter, her father being identified as Randall Fox Renwick.
- "The Daring Drummonds" by Brad Mengel (also refers to Mr. Breen's theory)
- "The Original Wold Newton Crossover Chronology" by Win Scott Eckert (references to Randall Fox Renwick)