Barr's debut as a comics professional came in DC Comics' Detective Comics #444, for which he wrote an eight-page back-up mystery feature starring the Elongated Man. Another Elongated Man story followed in Detective Comics #453. He wrote text articles and editorial replies in letter columns for the next few years. By mid-1980 he was writing regularly for both DC and Marvel, including stories for Mystery in Space, Green Lantern, The Brave and the Bold, Marvel Team-Up, and a Spider-Man/Scarlet Witch team-up in Marvel Fanfare #6. Legion of Super-Heroes #277 saw him take on editorial duties at DC, a position he would hold until 1987. In December 1982, he and artist Brian Bolland began Camelot 3000, a 12 issue limited series that was one of DC Comics' first direct market projects. Barr and artist Trevor Von Eeden produced the first Green Arrow limited series in 1983. When the long running The Brave and the Bold series came to its conclusion with issue #200, it featured a preview of a new Batman series, Batman and the Outsiders by Barr and artist Jim Aparo, which would be described by DC Comics writer and executive Paul Levitz as being "a team series more fashionable to 1980s audiences." The Masters of Disaster were among the supervillains created by Barr and Aparo for the series. Barr wrote every issue of the original series, and its Baxter paper spinoff, The Outsiders that did not include Batman and introduced Looker. After the series' cancellation in February 1988, it was revived in November 1993 by Barr and artist Paul Pelletier. He was one of the contributors to the DC Challenge limited series in 1986 and wrote the "" storyline in Detective Comics #575-578 which followed up on Frank Miller's "". Barr introduced the Reaper in Detective Comics #575 and returned to the character in the Batman: Full Circle one-shot in 1991. Another project from 1987 was the ' graphic novel which was drawn by Jerry Bingham, proceeds from which reputedly "restored DC Comics to first place in sales after fifteen years." This title, and Barr's work on Batman with artist Alan Davis have been cited by Grant Morrison as key inspirations for his own run on the Batman title. Barr's sequel, Batman: Bride of The Demon, was published in 1991. His other comics work includes Mantra for Malibu Comics and Maze Agency for and Innovation Publishing. Barr contributed to the Silver Age Sentinels anthologies of short stories from Guardians of Order. In 2007, he wrote a two-part story for the pages of DC's ', returned to the Outsiders with Outsiders: Five of a Kind — Katana/Shazam #1, contributed to Tokyopop's Star Trek: The Manga, and relaunched Maze Agency at IDW Publishing. He has scripted many of Bongo Comics' The Simpsons titles, including a Christmas story for 2010. In May 2010, the Invisible College Press published Barr's science fiction/fantasy novel, Majician/51, about the discoveries of a scientist working at Area 51. Barr has written every one of the first four incarnations of Star Trek: Star Trek,, and ', in either comic book or other media. Barr's Batman stories and scripts have been adapted into several mediums, including for episodes of '.
