Fafhrd and the Gray Mouser influenced Discworld

The Colour of Magic opens by parodying Leiber directly. Bravd and the Weasel, the two adventurers watching Ankh-Morpork burn in the first chapter, are Fafhrd and the Gray Mouser, a large barbarian and a small sly one, named closely enough that the joke only works if you know them. The city is the larger debt. Ankh-Morpork is Lankhmar rebuilt for comedy: a corrupt, ancient, river-split metropolis run by guilds and a patrician, where the Thieves' Guild is a licensed profession with paperwork. Pratchett began Discworld as a parody of the genre and picked the two writers most worth parodying, Leiber and Howard.