James Murdoch MacGregor (14 February 1925 – 22 July 2008[1]) was a Scottish journalist and author best known for writing science fiction under the pen name J.T.

Born in Paisley, Renfrewshire, Scotland, but living largely in Aberdeen,[1] MacGregor used the pseudonym McIntosh (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 literature, though he did publish books by his own name.

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

During 2010 the National Library of Scotland purchased his literary papers and correspondence.

[1] John Clute writes that "McIntosh never lost the vivid narrative skills that made him an interesting figure of 1950s sf, but his failure to challenge himself or his readers in his later career led to results that verged on mediocrity.