Xan

A NPC in the Baldur's Gate RPG who can join your party. He's a very good mage, and having him and Edwin in the same party can be a very potent combination. He's extremely pessimistic, coming in second only to Minsc in terms of comic relief.

"Our quest is vain..."
"Oh, what is the point?"
"If you want..."
"Why don't we just sit down in a nice quiet corner and wait to die?"
"The majesty of the forest makes me feel quite...insignificant."
"While I'm in charge, I shall do my best not to get us all killed.

Also, the big boss guy in Unreal Tournament. He was a robot/cyborg (whether there was a human in there changed, depending on the source), kind of short, with a funny looking antenna on top of his head. He was pretty badass... Especially annoying was his ability to always get the invisibility and shield belt powerups. Full name was Xan Kriegor.

Also in the open-source graphical MUD Crossfire, a type of flying insect annoying because (a) they're fast (b) they're poisonous. One isn't a problem, but the problem is that they attack in swarms. Xan's wings are quite valuable however, so it's a little consolation.

A fairly-high-level monster in Nethack represented by a red x. Their distinguishing feature is that they can prick your leg. The most noticeable effect of having your leg injured in this fashion is that you can become burdened. You also cannot kick things.

The pricking attack may also permanently decrease your strength.

While nothing besides a lump of royal jelly or non-cursed potion of speed or will make your legs heal faster, any permanent strength reductions can be fixed by a unicorn horn, or spell / potion of restore ability. Wearing boots usually protects your legs, but not always. Levitating keeps you out of its reach completely.