J. T. McIntosh is a pseudonym used by Scottish writer and journalist James Murdoch MacGregor (1925—2008).
Born in Paisley, Renfrewshire, Scotland, but living largely in Aberdeen, MacGregor used the McIntosh pseudonym (along with its variants J. T. MacIntosh, and J. T. M'Intosh) as well as "H. J. Murdoch", "Gregory Francis" (with Frank H. Parnell), and "Stuart Winsor" (with Jeff Mason) for all his science fiction work, which was the majority of his output, though he did publish books under his own name. His first story, "The Curfew Tolls", appeared in Astounding Science Fiction during 1950, and his first novel, World Out of Mind, was published during 1953. He did not publish any work after 1980.
In 2010, following his death in 2008, the National Library of Scotland purchased his literary papers and correspondence.

Along with John Mather and Edith Dell, he is credited for the screenplay for the colour feature film Satellite in the Sky (1956).