Marvel Comics
McGregor's first appearances in print were in the letters-to-the-editor columns of various Marvel Comics titles. After breaking in as a professional at Warren Publishing in 1971 with anthological science-fiction/horror stories for that company's black-and-white comics magazines, McGregor became a writer-editor at Marvel, beginning as a proofreader in late 1972. He soon became one of the 1970s wave of creators such as Steve Englehart, Steve Gerber and Doug Moench who took often minor characters and helped create a writerly Renaissance. Former Marvel editor-in-chief Roy Thomas said in 2007,
McGregor established himself with two series that remain among comics' most acclaimed: "Killraven, Warrior of the Worlds", in Amazing Adventures vol. 2, #21-39 (Nov. 1973 - Nov. 1976, except for fill-in issues #33 and 38); and "Black Panther", in Jungle Action #6-24 (Sept. 1973 - Nov. 1976, except for #23, a reprint).
Unusually for mainstream comics, the Panther stories were set mostly in Africa, in the Panther's fictional homeland Wakanda rather than in Marvel's usual American settings. As with the futuristic stories of Killraven, McGregor's settings were enough outside the Marvel mainstream that he was able to explore mature themes and adult relationships in a way rare for comics at the time. Like Jim Steranko, a direct influence who had pushed similar boundaries in the late 1960s, McGregor often found himself at the limits of acceptability with both Marvel and the Comics Code Authority. He and artist P. Craig Russell engineered color comic books' first known interracial kiss, between the "Killraven" characters M'Shulla and Carmilla Frost, in Amazing Adventures #31 (July 1975). Three years earlier, McGregor and artist Luis Garcia had already presented the first known interracial kiss in mainstream comics (as opposed to underground comix) in Warren Publishing's black-and-white horror-comics magazine, Creepy #43 (Jan. 1972), in the story "The Men Who Called Him Monster".
More than two decades after the "Killraven" feature ended, comics historian Peter Sanderson wrote that,
McGregor also wrote stories for the Marvel characters Luke Cage, Morbius the Living Vampire, and Spider-Man, and created the detective feature "Hodiah Twist", seen in the black-and-white magazines Marvel Preview #16: Masters of Terror (1973) and Vampire Tales #2 (1975).
Graphic-novel pioneer
With artist Paul Gulacy, McGregor created one the first modern graphic novels, Eclipse Books' Slow Fade of an Endangered Species. Published in August 1978 ... two months before Will Eisner's more famous, graphic short-story collection A Contract with God ... it led to a 14-issue spin-off series for Eclipse Comics.
McGregor went on to write two additional early graphic novels for Eclipse, each set in contemporary New York City and starring interracial-buddy private eyes Ted Denning and Bob Rainier: Detectives Inc.: A Remembrance of Threatening Green (1979), with artist Marshall Rogers, and Detectives, Inc.: A Terror Of Dying Dreams, with artist Gene Colan, who would become a frequent collaborator.
He has also written two prose books: Dragonflame and Other Bedtime Nightmares (Fictioneer Books, 1978) and The Variable Syndrome (Fictioneer, 1981).
Later comics
Other work includes the DC Comics' miniseries Nathaniel Dusk (1984) and Nathaniel Dusk II (1985—1986), both with Colan; and, for New Media Publishing's Fantasy Illustrated (1982), "The Hounds of Hell Theory", starring the husband-and-wife detective team Alexander and Penelope Risk, with artist Tom Sutton.
McGregor revisited the Black Panther with Colan in "Panther's Quest", published as 25 eight-page installments within the bi-weekly omnibus series Marvel Comics Presents (issues #13-37, Feb.-Dec. 1989); and, later, with artist Dwayne Turner in the squarebound miniseries Panther's Prey (Sept. 1990 - March 1991). Later in the decade, McGregor became one of the primary writers of the Zorro canon, with Topps Comics' Zorro and Lady Rawhide comic books; Image Comics' adaptation of the movie The Mask of Zorro; two years of the Zorro newspaper comic strip (with artists Tod Smith and Thomas Yeates, premiering April 12, 1999); and Papercutz's 2005 "American manga"-style Zorro series, which was collected as a graphic novel the same year.
