His Grace, The Duke of Ankh, Commander Sir Samuel "Sam" Vimes is a fictional character in Terry Pratchett's Discworld series. Vimes is depicted in the novels as somewhere between an Inspector Morse-type 'old-school' British policeman, and a film noir-esque grizzled detective. His appearances throughout the Discworld sequence show him slowly and grudgingly rising through the ranks of both police force and society. As of his latest promotion, his full name and title is stated as being "His Grace, His Excellency, The 1st Duke of Ankh; Commander Sir Samuel Vimes". When serving as Ambassador for Ankh-Morpork, he is also referred to simply as "His Excellency", and is also nicknamed "Blackboard Monitor Vimes", "Vimes the Butcher" and "Vetinari's Terrier". According to his wife, Sybil, Vimes is recognised by many as Lord Vetinari's right-hand man.

Discworld is a comic fantasy book series written by the English author Terry Pratchett, set on the Discworld, a flat planet balanced on the backs of four elephants which in turn stand on the back of a giant turtle. The series began in 1983 with The Colour of Magic and continued until the final novel The Shepherd's Crown, which was published in 2015, following Pratchett's death. The books frequently parody or take inspiration from classic works, usually fantasy or science fiction, as well as mythology, folklore and fairy tales, and often use them for satirical parallels with cultural, political and scientific issues.