Sin Killer is a historical novel by American writer Larry McMurtry. It is the first, both in chronological and publishing order, of The Berrybender Narratives. It was published in 2002. Set in 1832, the book follows the adventures of a clan of eccentric British aristocrats and their retainers as they begin a hunting expedition up the Missouri River.

Cover of the first edition, published by Simon & Schuster

The title refers to the nickname given to frontiersman Jim Snow, a Berrybender ally who violently hates sin of all kinds.