One of the more interesting super-villains to be battled by the X-Men when they were still wearing yellow-and-blue jumpsuits rather than leather fetish gear, Unus (real name Gunther Bain, originally Angelo Unuscione) had the knack of projecting a force field from his body which protected him from harm. The force field was amazingly selective and intelligent - for example, throw a knife at him and it would bounce off an invisible barrier two feet away from his skin, but pass him the same knife for slicing up a tomato, or throw him a baseball, and nothing would happen.
So far, this sounds like a really wonderful power. Unfortunately, Unus was a bad guy. He had the jaw and the eyebrows to prove it, and was a member of two truly naughty and nefarious organizations: Factor Three (nothing to do with sun screen), and, even better, The Brotherhood Of Evil Mutants (I mean, who thought that one up?). These two gangs specialized in making life unpleasant for the X-Men in between planning to utterly rid the world of pesky non-mutant types.
Unus was a bad guy, and this is where the tragedy sets in. Bad guys with interesting powers invariably end up with their powers being used against them, presumably to demonstrate the power of karma in some way, and Unus was no exception. The X-Men were racking their brains trying to come up with some way of kicking the crap out of someone whose force field protects them from all harm, and finally the Beast (Hank McCoy) comes up with a great idea - he will befriend Unus, who unfortunately isn't too bright, and then use a special machine of his own design to increase Unus's powers!
Increase? That's right! Beast boosts Unus's force field so that it repels everything, not just threatening or dangerous objects. Cue multiple frames of a confused and increasingly upset super-villain reaching for cigarette packets, chairs and plates only to watch them fly away from him. In a final ignominy, the X-Men find him in the kitchen, flailing after a flying steak in a paroxysm of hunger. Because this is a family drama, kids, Unus's clothes don't fly off - or maybe they were just a big tattoo and I've been fooled all this time.
I always wondered why the X-Men didn't get Beast to point the machine at all of them - "Me! Me! Increase my powers!" - unless the machine was somehow designed specifically to increase mutant powers in a bad way. For instance, if it was used on Cyclops, his eye beams might suddenly blow off the front of his skull. Or if it was used on Wolverine, his healing ability might go nuts and he would start growing ears and noses and hair and extra arms and legs all over his body. It wouldn't be pretty at all. Maybe the lesson is this: Good guys like their powers just the way they are.
Back to poor old Unus. He became one of the rare deaths in the Marvel Comics universe when his force field went out of control all on its own and started pushing everything away, even air molecules. Cue tragic scene of Unus floating helpless in the middle of a giant circus tent, starving and suffocating to death, until he finally goes limp and falls into the arms of his best friend, The Blob. Cue agonized cries of "WHY!?!?!?" The Blob subsequently goes on a rampage through the city, until Spider-man stops him and he starts to cry. It's okay to show your feelings, even if you're a super-villain.
Facts about Unus the Untouchable: http://www.sigma.net/ozbot/marvelhandbook/rtuw/unus.htm