The first few stories in Leiber's popular Swords series: one each for Fafhrd and the Gray Mouser on their own, and one that describes how they met. In these editions the short stories were sensibly rearranged into plot order rather than the order they were written, so the second story here predates the others by several years.
This is exceptionally well-written swords-and-sorcery fantasy with plenty of comedy thrown in:
Fafhrd stopped, again wiped right hand on robe, and held it out.Name's Fafhrd. Ef ay ef aitch ar dee.
Again the Mouser shook it.Gray Mouser,he said a touch defiantly, as if challenging anyone to laugh at the sobriquet.Excuse me, but how exactly do you pronounce that? Faf-hrud?
It's notable as the universe that the first Discworld book set out to affectionately parody; Discworld fans will recognise several characters and situations from the Rincewind stories here. (It might be coincidence, but there's a bit in "Feet of Clay" that's awfully similar to the start of "Ill Met In Lankhmar" too.)
Thoroughly recommended -- and, fortunately, it's an easy series to get hold of second-hand.