Well, for the sciences, you'd probably have the heads or "chiefs" of whatever subdepartments there were... Astrobiologist, Geologist, Astrophysicist, etc.
In security, you might have specialists in certain fields. Same with communications. You might have a Cryptologist, Linguist, or a Weapons Specialist or Armory Officer.
And of course, the Assistants to each of your Department heads.
Counselor or Psychologist.
If it's a ship or station with families, no doubt Pediatrician and even a Schoolteacher could be a job held by a non-civilian.
The E-E was even supposed to have a Librarian.
"It's hard being an evil genius when everybody else is so stupid" -- Quantum Crook