Farthing is an alternate history novel Welsh-Canadian writer Jo Walton and published by Tor Books. It was first published on 8 August 2006. A sequel, Ha'penny, was released in October 2007 by Tor Books. A third novel in the series, Half a Crown, was released in September 2008, also from Tor, and a short story, "Escape to Other Worlds with Science Fiction", was published on Tor.com in February 2009.