Martin Day (born 1968) is a screenwriter and novelist best known for his work on various spin-offs related to the BBC Television series Doctor Who, and many episodes of the soaps Fair City, Doctors and Family Affairs.
Day's first published fiction was the novel The Menagerie in 1995, published by Virgin Publishing as part of their Doctor Who Missing Adventures series. Following the withdrawal of Virgin's licence to produce Doctor Who novels, Day moved to BBC Books, who published the novel The Devil Goblins from Neptune in 1997. The novel (co-written with Keith Topping) was the first of BBC Books' Past Doctor Adventures series, and was quickly followed by The Hollow Men in 1998 - again written with Topping. 1998 also saw the publication of Another Girl, Another Planet by Virgin Publishing. Co-written with Steve Bowkett (under the pseudonym Len Beech), this was one of the first books in Virgin's line of Bernice Summerfield novels.
Following these novels, Day returned to solo writing, and to the Past Doctor Adventures range in 2001 with the novel Bunker Soldiers. This was followed in 2004 by the novel The Sleep of Reason, one of the final Eighth Doctor Adventures to be published and perhaps his most popular novel. Between 2000 and 2001 Day wrote nine episodes for Five's Family Affairs, and in 2005 he started writing for BBC One's Doctors. In 2008 he was lead writer on Crisis Control, a new series for CBBC; Day storylined all thirteen episodes. In 2015 he started writing for RTÉ One's soap Fair City.