Last session, the PCs ran into some two-headed ogres. Naturally, having played D&D-based games in the past, they identified them as ettins.
It's quite possible "ettin" is a term for a two-headed ogre. But I just refer to them myself as two-headed ogres, and it's generally wiser to make sure you're not bringing inaccurate assumptions in from other games.
I felt like talking about the Felltower ogres though, so here is a look at these all-too-common threats.
Some two-headed ogres and a "normal" single-headed ogre.
Here is what is known about ogres in DF Felltower:
They are Stupid
Ogres, in general, are very stupid - IQ 7 is the racial average. Consider that IQ 6 is high-end primate, and even dull-witted types are generally IQ 9, and you can get some idea of how frustratingly stupid they are. The DFRPG Monsters book describes them as "phenomenally stupid" - emphasis in the original. You can negotiate with them, but it's hard to do so with any productive result.
There are exceptions, however - the occasional ogre is very clever, for an ogre (IQ 8 or even a Leonardo-like IQ 9).
And there are rumors of very smart ones.
There is even some that tell of the ogres once being very intelligent, magic-using beings whose wizards risked too much and caused the collapse and warping of their race. Other versions of the tale have the Good God smiting them down for their turn to evil, and making them as stupid as their actions were.
They are Hideous people-eaters
They have Appearance (Hideous) and the Odious Racial Habit (Eats other sapient beings, -3 reactions). Since pretty much everything that isn't an ogre doesn't like ogres, they're used to hostile reactions. They're equally hostile back. They aren't evil per se, but they act with total disregard for the feelings and interests of other beings.
They're normally kept in line by their allies with threats and bribes.
They are big and strong and tough
Even a weak ogre is as strong as the strongest non-barbarian humans. They only get larger and stronger from there. They're vulnerable to sheer physical damage as they aren't supernatural. They're magic resistant, poison and disease resistant, and pretty much fearless.
They come in varieties
Ogres come in a variety of colors, shapes, and sizes. They have a tendency towards physical defects - different-sized arms, warped or bowed legs, misshapen heads, oversized hands or feet, etc. Some are horned. And some rare few are two-headed.
Here are some varieties:
Aquatic - slimy-skinned ogres with webbed fingers and toes that dwell in swamps and fens.
Two-Headed - some ogres have two heads, side by side. They aren't any smarter, act stupider, and rumors claim you can't kill them without slaying both heads.
Giant - some ogres are very large - SM+2 or more, not the standard SM+1. This type can be combined with the other types. Some "giants" in stories and rumors were just over-sized ogres.
Fachan - the rarest of ogres, they have one fused leg, one eye, and one central arm.
It's also possible the Siege Beast is just a larger, stronger, smarter variety of ogre. It's not clear, though, and that's largely based on fairly similar appearances.