- Medusa: A nicely proportion gal with looks that can kill.
- Beholder: It's smart, it's evil, and it can Nerf casters with a glance.
- Gas spore: a worthless monster other than psyching out those players who memorized the Monster Manual.
- Crypt Thing: It' looks like a lich, but more chatty. Once you honk it off it will "disintegrates" a party member by teleporting them a thousand miles away (or paralyzing them and making them invisible).
- Rust Monster: I love seeing the Fighter types scream and move to the back of the party when this cute little beast shows up.
- Lich:Undead arch mages or high priests, great behind the scenes villains, and hard core combatants when prepared.
- Shuggoth/Gibbering Mouther: I was privileged to have the First Edition Deities and Demigods that contained the Cthulthu Mythos. The Gibbering Mouther is an obvious nod to the truly frightening Shuggoth: 10 tons of Jello sprinkled with eyes, mouths and limbs that just want to give you a full body hug.
- Drow: A late addition to the OD&D school, but very capable opponents with no real weaknesses. I also enjoyed the "take back" effect that their equipment had. The DM could hand out tons of +5 magic items only to have them become worthless in the surface world.
- Xorn: Treasure eating, trilateral symmetric, intelligent rock. Aside from the Gibbering Mouther it's the most alien of the OD&D creatures.
- Flesh Golem: Frankenstein's Monster in D&D form. Strong, largely invulnerable, but can get a little crazy every now and then.
My Top 10 Favorite Monsers
Several other blogs that I read have been doing the their top ten favorite monsters (here, here, here, and here). Not being one to miss a meme I present to you mine. (Though most are OD&D).