In his role as editor, Pabst oversaw the writing staff of the magazine and its in-house illustrator. His responsibilities included setting the pay rate for the writers and selecting which story would be featured on the cover each month. He was also in the position of enforcing the decisions of the magazine's publisher, a fact which brought him into conflict with Benny Russell when the magazine refused to publish the latter's story about a black captain of a futuristic space station. (DS9: "Far Beyond the Stars")
Pabst was played by actor Rene Auberjonois.
"Far Beyond the Stars" story writer Marc Scott Zicree originally intended for Pabst to be portrayed by Armin Shimerman. That idea was nixed by Ira Steven Behr, an outcome Shimerman himself was very happy with, for a multitude of reasons. 
The writing staff originally thought that Pabst would be played by J.G. Hertzler. The role of the editor became a larger and more significant part in the story, which was instrumental to Rene Auberjonois being cast as the character instead. (AOL chat, 1998)
Ira Steven Behr once described the Pabst character as an "unenlightened white man." Rene Auberjonois recalled, "Ira was very concerned about how I would react to being the only one of the principal characters to be, essentially, a bad guy. But I loved the part. And I don't necessarily see Pabst as 'the bad guy.' He was a peripheral character, and the only one [in 'Far Beyond the Stars'], aside from Benny, whose viewpoint went through a whole process." Although Auberjonois usually played Odo on Star Trek: Deep Space Nine, the actor had no difficulty with separating Pabst from Odo in his performance choices. (Star Trek: Deep Space Nine Companion, p. 535)
In the novelization of the episode, Pabst had been receiving stories from Russell long before the latter worked for Incredible Tales. The story that led him to hire Russell featured a partially robotic alien race, and it was Pabst who came up with the opening line for it – "Resistance is futile."
The authors of the Star Trek Encyclopedia (4th ed., vol. 2, p. 119) thought Douglas Pabst "may have existed in reality, or perhaps only in certain reaches of Ben Sisko's mind."