John Thomas Phillifent (November 10, 1916 – December 15, 1976) was an English science fiction author. He wrote as John T. Phillifent and under the pen name John Rackham. Most of his work was published as by Rackham, the main exceptions being three novels related to The Man from U.N.C.L.E. series, his short stories published in the magazine Analog, and a number of late novels. Most of his novels were issued together with the works of other authors as Ace Doubles.
American author Frederik Pohl credits Phillifent with a compehensive definition of science fiction that he dubs “Rackham's Law”. According to Pohl, Phillifent's opinion of “the diagnostic cut … between science fiction and all other forms of writing” was that science fiction “was unique in that it was invariably written by 'the science-fiction method' analogous to the 'scientific method' which … underpins all science.” Pohl's own description of “the science-fiction method” (which Phillifent himself never troubled to define) is that “it consists in looking at the world around us, dissecting it into its component parts, throwing some of those parts away and replacing them with invented new ones - and then reassembling that new world and describing what might happen in it. And I think that every SF writer who ever lived has used precisely that method.”