Most useful monster for the DM

[Lithorn]

Which monster do you find most useful to oppose the players out the monster manuals? I've always considered orcs to be in this position, seeing I usually DM low level groups and orcs are commonly found, tough when armed well, and usually travel in large packs. The PC's rarely play an adventure and don't encounter orcs.

[Gnolyn Lochbreaker]

Depends on the character level really...and the world you're using. I find orcs a little over-used myself. I prefer using Lizardmen, troglodytes and ogres when I can. But it really is hard to find something that's challenging at low levels and at higher levels: dressing orcs or goblins up in +1 platemail with magical weapons, throwing in an orc wizard and a shaman or two....just gets boring. Variety is the spice of life! While it's nice to have a common enemy for a campaign or two, it becomes 'old hat' pretty soon. I think it bores players when they keep running across the same thing all the time. "Oh, look another hob-goblin. Oh, wow, this one has PLAID armour!".

Having said that though, I do have ones I really like to use when I can In addition to the others I mentioned above, minotaurs and giants are another favourite of mine. I think it adds something when a creative player can fast-talk themselves out of a fight, or at least get in some good trash talking

[kemanmaldea]

And then there is the posibility that you could have your players meet up with a friendly monster that is way powerfull for the purpwse of plot development and depth.

example:
Players are hired by a woman to tack a caravan to a city along the way they meet and talk with an Anchant Gold dragon. The dragon tells them that they are involved with a feud between two other dragons.

Other than that there is the fairly well known trick of leveling monsters but I wouldnt use a too common one like orcs.

[Vormaerin]

I don't know about 'most useful', but my favorite monster is the Stirge. They aren't terribly dangerous, but lots of fun to use and a threat for a goodly while. Also easy to explain in a wide variety of circumstances. I much prefer the more birdlike imagery of 1st edition to the bug like 3rd edition, though.

For my generic 'villain race', I also prefer the reptilian or fishy types. Sahuagin are really cool, if limited in locale. Yuan ti, lizardmen, troglodytes, etc usually get my pick over the more common orcs and hobgoblins. Yuan ti work well because you can have those pesky infiltrator types more easily than with orcs and such.

Aloha
Vormaerin

[Azardu]

Kobolds!

Hehe, and Stirges are evil

[Lokken]

a mercenary group of planetouched. NPC local villains. As for just monsters, there's a lot of undead that can suit lowlevel party. Like skeletons and some zombies

[Kerric]

Undeads all the way
First of all they are realy cool.
Second the players hate them, cause of the ability to ignore 50% of the hits, unless its a Ghost Touch weapon.
Ability Drain to realy annoy the players.
Impossible to critical hit a undead too.
just got to love them