As a new SG, I'm arranging an introductory adventure that is going to include an opportunity for combat (if nothing else, to help us understand it and see it in action). I was wondering how more-experienced SGs deal with characters who are, essentially, just there to get beat up. Do you work them out based on the character creation rules? Build a complete character but assign the stats arbitrarily based on the level of difficulty you want to establish? Just a skeleton of a character, with nothing more than an attack score and wound levels?
If they're just there to get beat up? 3rd option. Don't bother statting them out. They have a weapon score of 5 and a relevant stat of 2. related (but non-primary) abilities are 3. Non-relevant stats are 0. That's it.
If, for whatever reason, they start being relevant? Add on things as you need them; use meta-abilities (short adjective/noun pairs) that describe their history, and use that to characterize them. don't bother giving virtues unless they REALLY becomes relevant NPC's somehow.
Example:
- Generic soldier. Str and Sta at +2; everything else 0. Weapon ability 5; brawling and other things at 3; that's all you need.
- If you need him to be characterized slightly? Give him the following 2 meta-abilities: for example, "Experienced Soldier" and "Smuggler's son" - that's enough to get some decent characterization for a while.
- If he starts being a regular cast member, slap on some virtues and flaws. If you ever give him XP, write him up fully.
For minor but actual threats to grogs, I use a slightly more fleshed out version than Kevin does, but you don't really need much.
Work up a few thug types and the can spear-carry as bandits, guards, or opposing grogs.
I've also been known to use copies of turb grogs against player grogs, for more challenging situations.
RoP: Faeries have Faeries whose role is to be defeated 
When I have to have mook level enemies (they are just an annoyance before reachig the boss) I usually do this:
Init: 1-3
Attack & defence ability: 8
Damage: 2+weapon damage
Relevant skills: 4 (Typically Awareness or Stealth)
Soak 2+Armor worn
Health: 3 levels
Heavy wounds count as 3
Medium wounds count as 2
Light wounds count as 1
So they die at 1 Heavy wound, 3 light wound or a medium + 1 light
This gives me with a bunch of unimportant mooks who can be a danger and easy to bookkeep. Then I just describe them differently with what weapons they have and if they look scarred, muscular, tawny etc.
Another option is to just treat them as a variant Swarm (although technically an adaption of the "Troop" type from say PFRPG or similar might be a better analogy).
Depends on what the role of the mooks in the story is - if they're not designed as a significant threat the abstraction may be the way to go.