On a bit of a sillier note, these are characters my Acolytes may meet on a kill-team style mission at some point past their first investigation, as a bit of a humour break from grim darkness and dark grimness. Any thoughts about statting them out? I'm thinking about representing them as a Guard unit gathered from various "lone survivors" in various battles across the sector and chosen for near-suicidal missions that don't quite qualify for Space Marine presence.

My thoughts:

Scout: Salvar Chem-Dog Veteran

Soldier: Mordian Iron Guard Sergeant

Pyro: Death Korps of Krieg Combat Engineer

Demoman: Vostroyan Firstborn Grenadier

Heavy: Valhallan Ice Warrior Heavy Weapons Gunner

Engineer: Techpriest Enginseer

Sniper: Catachan Jungle Fighters Sniper

Medic: Armageddon Steel Legion Medic

Spy: Jopall Indentured Squadrons Battle Psyker

For the Chem-dog you could make good use of the Penal Legion trooper alternate package (Radicals Handbook if memory serves). Hiver of Forge World should cover the origin. An injector-collar or possibly an implant is pretty much a must. Punk hairdo optional.

Mordian Sergeant: Guardsman with a nice fat Willpower stat to start off with and as many of the "disciplined" and "teamwork" talents as you can pile on with. Probably use "Mesh Cowl" stats for his gunny hat. Hive world origin, probably modified to grant Darksight since Mordians live on the permanently-dark side of their homeworld. Sharp bayonet and crisp uniform is a must!

Catachan, use the Death World origin package from Rogue Trader in place of a DH homeworld pick. Procede to Guardsman and enjoy. Make sure to give this guy a nice beefy combat knife from Inquisitor's Handbook and mono that bad-boy! Also include a red bandana in his kit since earning this is a rite of passage into adulthood on Catachan.

For the Vostroyan medic, go with Adept (to make him a GOOD medic instead of a trooper with band-aids) and then be sure to pick up some weapon training for him. Don't forget the carapace armour for this guy! Any weapons should be fancy hand-crafted antiques with plenty of stout wood and shiny brass plating.

Steel Legion trooper: Hiver/Guardsman and be sure to pick up the Drive (ground) skill and if they are a veteran add Hatred (Orks). Flak Greatcoat & helmet should replace standard guard armour (same stats, different look)

Death Corps trooper: Like the Catachan above, use the Death World origin from RT, but instead of making him "Rambo" give him an absolutely **** Fellowship (As in shittier than the Techpriest!), a respirator and a name like "Trooper 247 Gamma" or something equally dehumanized. On the plus side, if anyone has the Fearless talent as an elite advance, it is this walking proto-corpse! Same armour changes for this guy as the Steel Legion trooper.

Valhallan trooper: Pretty straightforward. Make sure they have Resistance (Cold) and Hatred (Orks). Should complain about the "warm weather" while scraping ice off the team's transport vehicle... Bonus funny value if he hero-worships a certain Commisar. Replace IG armour with Flak Greatcoat and helmet OR mesh-reinforced fur hat.

The others should be pretty straightforward. Sounds like fun!

DERP! I mixed a few of your ideas up. The general idea stands, just move my thoughts around to the appropriate PBI....

Penal Legion Trooper package on a combat Psyker should prove interesting.