Ha'penny is an alternative history novel written by Jo Walton and published by Tor Books.

The book is a mystery thriller set inside an alternative history in which the United Kingdom made peace with Adolf Hitler in 1941.

When a bomb explodes in a London suburb, Scotland Yard Inspector Peter Carmichael is assigned to the case.

He finds a web of conspiracy and a plot to murder both Britain's new Prime Minister and Adolf Hitler during the latter's Friendship visit to London.

The Los Angeles Times named Ha'penny one of their ten Favorite Mystery Books of 2007.