Heard: "X-Files: trust no one" edited by Jonathan Maberry, 2015, overdrive.com download. Multiple narrators.
Short story collection featuring Scully and Mulder with one story focusing on Skinner. I heard about the book because I (sort of) follow Jonathan Maberry online. Fun to listen to and a nice tie-in to the upcoming episodes.
All the stories list the time and date like each TV episode does. Most stories were set during the first half of the television show's run. One earlystory has Mulder's wife. Mulder married a woman so she could earn status as a legal immigrant. I think another story was set post-2000 with Scully thinking about her partnership with Mulder as more than work.
All the shapeshifter stories you could ever want. I enjoyed those shapeshifter TV episodes as well, so I will not slight the authors for enjoying the same thing. A few appearances of The Smoking Man. Several stories where super secret men in hazmat suits swoop in, take over a crime scene, and concoct a cover story.
I don't recall all the authors. I do remember Max Allan Collins and W.D. Gagliani. Collins's story was a horror tale. Gagliani had werewolves, of course.