In the 1970s, MacIntyre worked for a Manhattan publisher of pornographic novels.
Employees were paid $175 per week and expected to produce an entire pornographic novel in that time, as well as a chapter for a compilation-format pornographic book supposedly assembled from the cases of a Dr. Lamb.

Although MacIntyre professionally published many works of non-fiction and literature, he is best known as an author of genre fiction: specifically, science fiction, fantasy, horror and mystery stories.
His short stories were published in Weird Tales, Analog, Asimov's Science Fiction, Amazing Stories, Absolute Magnitude, Interzone, the Strand Magazine and numerous anthologies, including Terry Carr's Best Science Fiction of the Year #10, Michael Reaves and John Pelan's mystery/horror anthology Shadows Over Baker Street, James Robert Smith and Stephen Mark Rainey's horror anthology Evermore, and Stephen Jones's The Mammoth Book of Best New Horror.
For Mike Ashley's The Mammoth Book of Historical Detectives (1995), MacIntyre wrote "Death in the Dawntime," a locked room mystery (or rather, sealed cave mystery) set in Australia around 35,000 BC, which editor Mike Ashley suggests is the furthest in the past a historical whodunnit has been set.

A characteristic of MacIntyre's writing (both fiction and non-fiction) is his penchant for coining new words and resurrecting obscure words.
Language authority William Safire acknowledged MacIntyre's neologism of "Clintonym" and quoted his historical etymology research.

In addition to publishing science fiction in Analog, MacIntyre also contributed to that magazine as an artist, illustrating his own stories and one by Ron Goulart.

MacIntyre wrote a considerable number of book reviews for The Magazine of Fantasy & Science Fiction.
In the July 2003 issue of that magazine, MacIntyre mentioned that he was related to the wife of Scottish author Eric Linklater.
It is unclear whether this was one of the many fabrications about his life that MacIntyre's brother later confirmed to be untrue.
MacIntyre had previously stated (in interviews and at science-fiction conventions) that he was estranged from his abusive family and did not acknowledge them.
He had legally changed his name, officially filing a deed poll: "Fergus MacIntyre" was therefore his legal name but not his birth name.
He had acknowledged that he took the name "Gwynplaine" from the protagonist of The Man Who Laughs, a novel by Victor Hugo.

MacIntyre claimed to have contributed substantial script material to a 2006 documentary about actress Theda Bara, The Woman with the Hungry Eyes: he claimed his contributions included the film's title and an interview he had conducted with author Fritz Leiber.
He is only listed under the "Special Thanks" section of the credits; MacIntyre claimed to be contractually prevented from receiving a screenplay credit.
In the 1970s, MacIntyre worked for a Manhattan publisher of pornographic novels. Employees were paid $175 per week and expected to produce an entire pornographic novel in that time, as well as a chapter for a compilation-format pornographic book supposedly assembled from the cases of a Dr. Lamb.
Although MacIntyre professionally published many works of non-fiction and literature, he is best known as an author of genre fiction: specifically, science fiction, fantasy, horror and mystery stories. His short stories were published in Weird Tales, Analog, Asimov's Science Fiction, Amazing Stories, Absolute Magnitude, Interzone, the Strand Magazine and numerous anthologies, including Terry Carr's Best Science Fiction of the Year #10, Michael Reaves and John Pelan's mystery/horror anthology Shadows Over Baker Street, James Robert Smith and Stephen Mark Rainey's horror anthology Evermore, and Stephen Jones's The Mammoth Book of Best New Horror. For Mike Ashley's The Mammoth Book of Historical Detectives (1995), MacIntyre wrote "Death in the Dawntime," a locked room mystery (or rather, sealed cave mystery) set in Australia around 35,000 BC, which editor Mike Ashley suggests is the furthest in the past a historical whodunnit has been set.
A characteristic of MacIntyre's writing (both fiction and non-fiction) is his penchant for coining new words and resurrecting obscure words. Language authority William Safire acknowledged MacIntyre's neologism of "Clintonym" and quoted his historical etymology research.
In addition to publishing science fiction in Analog, MacIntyre also contributed to that magazine as an artist, illustrating his own stories and one by Ron Goulart.
MacIntyre wrote a considerable number of book reviews for The Magazine of Fantasy & Science Fiction. In the July 2003 issue of that magazine, MacIntyre mentioned that he was related to the wife of Scottish author Eric Linklater. It is unclear whether this was one of the many fabrications about his life that MacIntyre's brother later confirmed to be untrue. MacIntyre had previously stated (in interviews and at science-fiction conventions) that he was estranged from his abusive family and did not acknowledge them. He had legally changed his name, officially filing a deed poll: "Fergus MacIntyre" was therefore his legal name but not his birth name. He had acknowledged that he took the name "Gwynplaine" from the protagonist of The Man Who Laughs, a novel by Victor Hugo.
MacIntyre claimed to have contributed substantial script material to a 2006 documentary about actress Theda Bara, The Woman with the Hungry Eyes: he claimed his contributions included the film's title and an interview he had conducted with author Fritz Leiber. He is only listed under the "Special Thanks" section of the credits; MacIntyre claimed to be contractually prevented from receiving a screenplay credit.
F. Gwynplaine MacIntyre