Most of my recent Feng Shui work has revolved around demons. Yes, your heavy-hitters should be scary, but even Big Name Nastiness needs a few layers of "mook armor" to make the fight last a little longer. He's an overview of unnamed demons you can use for demonic hordes:
Gnarled Marauder (Main rulebook, p. 191?)
Your basic hentai tentacle trooper. AV of 8 is a bit of a yawner, and the creature powers are a bit uninspiring, particularly when you realize that those schticks sunk into Tentacles x6 are largely just fluff/flavor (you don't keep track of wound points on unnamed GMCs). However, give one of these things a name and all of a sudden you have to do 120 wounds worth of damage just to get at this thing's body.
Snake Men (Main rulebook, p. 191?)
Another AV of 8, which means your average housecat might find them "mildly annoying". Poison... eh, a bit weak, but nice to see an alternative damage type. And then another example of a useless Wound-based schtick on a mook, Regeneration. Nothing really interesting or evocative here, until you get to the schticks and notice they have the entire Path of the Tightening Coils, one of the most abusable Fu paths in the main book. Which is great until you realize their AV is too low to hit anything.
Bloodhunters (Marked For Death, p. 21)
Much more respectable AV of 10. Decent damage, and Flight is nice, but again, Regeneration is pointless. Kind of "vanilla" grunt demons, nothing flashy but they get the job done.
Skittering Demon (Marked For Death, p. 75)
Hmm... never noticed how wonky these things are. No Creature Power AV listed, and somehow their claw damage bypasses armor and Toughness with some unknown schtick/ability. Largely meant to just hassle or keep the players busy, we have one or two interesting schticks here that might lead to some interesting stunts (mostly the Glutinous Goo), and the Rancid Breath helps make up for the pathetic Body and claw damage. While there are some technical problems in the stat block, they generally succeed with what they were designed to do.
Kun Kan (Earth Demons, Back for Seconds, pp. 29-30)
These things are oozing with interesting flavor, and some solid potential here for earth-based stunts. Mechanics-wise... no by-the-book creature schticks, and the selection of unique schticks have several situational limitations. I love the "drag underground" attack, and their AVs are high enough to make them dangerous. I would have liked to see some of the creature schticks from the rulebook used here, but the unique stuff is very evocative and creative.
Popcorn Demons (Thorns of the Lotus, p. 45?)
Another demon without Creature Powers. "Hard to Kill" was a bit puzzling, until I realized that some savvy players might want to avoid the "Blaze of Glory". However, anything longer than 1 or 2 sequences essentially takes them out of the fight. Blaze of Glory makes these guys worth it, though... used properly, a few explosive chains could quickly pile up into massive damage. A very interesting surprise to spring on your players and make them think twice before plowing into melee.
Plain Old Ogres (Elevator to the Netherworld, p. 81)
Worthless AVs, and nothing really here that says "big and ugly". The worst crime, however: BOOOOORING.
Belching Ogres (Elevator to the Netherworld, p. 81)
Here we go, a bit more interesting. Basically a walking catapult/cannon/shotgun/blaster... a one-trick pony, but you can get a lot of mileage out of that pony with some creative projectiles. Worthless for anything else, but essential for adding ranged attacks and fire support to any demonic forces.
Imps (Elevator to the Netherworld, p. 82)
Opposite of Ogres, eh? And that would be... still BOOOOORING.
Unnamed Wang Liang/Black-Faced Ogre (Blowing Up Hong Kong, p. 40)
Ok, only slightly more interesting that Plain Old Ogres, but quite a few more points here for cultural/mythological accuracy. Decent AVs, and Rancid Breath x2 gives it a respectable source of alternative damage. Also, Info: Fishing 17. I'd like to see more of GMCs with obscure Info skills that add interesting flavor.