Carl Peterson is the alias of a criminal mastermind who was thwarted by Bulldog Drummond, in the novels by "Sapper" and Gerard Fairlie. Among his crimes was an attempted communist coup d'etat in the UK. His wife or mistress Irma Peterson subsequently sought revenge against Drummond when Carl himself was thought dead.
Philip José Farmer discusses Carl Peterson in Doc Savage: His Apocalyptic Life, and notes that Irma's habit of posing as Carl's daughter might hint towards a genuinely-incestuous relationship between the pair. He identifies Carl Peterson as the brother of Dr. Caber, with their parents being Urania Moriarty and John Clay, thus making Carl a Wold Newton Family member just as much as Bulldog Drummond is.
Rick Lai discusses aspects of Carl Peterson's career in his article Partners in Crime: Fu Manchu & Carl Peterson, identifying him as one of the eponymous villains in the Hercule Poirot novel The Big Four. His article A Brief Biography of Dr. Caber suggests that Dr. Caber, rather than Carl, was Irma's father. This theory is supported by an amusing letter sent from Dr. Caber to Carl Peterson, uncovered by Mr. Lai and published in Win Scott Eckert's Crossovers (see entry for The Gold Bat by P.G. Wodehouse, occuring in 1901).