Busman's Honeymoon is a 1937 novel by Dorothy L. Sayers, her eleventh (and last) featuring Lord Peter Wimsey.

Lord Peter Wimsey and Harriet Vane marry and go to spend their honeymoon at the country house, Talboys, which he has bought as a present for her. What is supposed to be a break from their usual routine of solving crimes (him) and writing about them (her) turns into an investigation of how the man Lord Peter bought Talboys from ended up dead at the bottom of the basement steps with his head bashed in.

(A "busman's holiday" is when a man who drives a bus for a living takes his family on vacation and ends up driving the car the whole time, so for him it's no break from his usual routine.)

Busman's Honeymoon first saw the light of day as a stage play by Sayers and Muriel St. Claire Byrne, which opened in December 1936.

A 1940 film version, based as much on the play as on the novel, starred Robert Montgomery as Peter and Constance Cummings as Harriet. The movie was released in the United States as Haunted Honeymoon.