I love the ash monsters in Morrowind. They start out just as regular-ish Ash Slaves, but once they get to Ash Zombie, THEY HAVE NO FACE. And then they get to Ash Ghoul and have a worm-trunk-thing where their eyes should be... and once they get to Ascended Sleeper level, they've got a full-on giant squid for a head... but when killed, their skull is the only thing left! I always took that as the skull being the only thing remaining of their original bodies, and the rest of their form (tentacles, robes, and all) is a "living dream" of their ascended selves.*
The other would probably be the Winged Twilights, also from Morrowind. They were always my preferred summon because they're quite tough and quite strong, and they only have a melee attack which makes them safe to use against enemies with spell reflection, and it makes them predictable (which is good for a summon). Plus they have virtually the same face as Breton women, which is kinda spooky.
*This only really makes sense if the godhead thing is actually canon.