There are many strategies possible. Can you describe this person's behavior more specifically?

I treat them with respect, kill them with kindness and keep my mouth shut on all sensitive objects - it works after a while.

I do as I do in life. Ignore them as much as I can without impeding work, and expose their acts.

The key, of course, is not to do anything, or say anything, that would get you in trouble...with your employer or anyone in the workplace. Just do your job, stay alert to the means by which this person might attempt to bring difficulty upon your life at work, as well a upon others with whom you work. New employees are especially vunerable, trying to establish themselves in the social workplace. Whatever you do, do not be drawn in by anyone who would cast ill will about another employee...or your employer. That person may be the backstabber setting the foundation, and may be attempting to add you to his/her "circle". For example, let's say an employee says that another employee dresses like a tramp. Let's say you privately hold the same opinion. Keep it to yourself. If you openly agree, the backstabber will have you by the short hairs, as it were, and will move on to recruit another employee making the same remark, except this time, he/she will say so-and-so dresses like a tramp...and GUAVA GODDESS agrees with me! That's how it starts...and that's how they work. There are hundreds of examples like this. You can listen to assess the devious bastard's information, opinions and methods...but never, never get drawn into it. In most solid organizations, backstabbers and the like do not prevail for very long or, if they do, are not very successful in the long run. Take it from an old man who enjoyed a very successful 30-year career in one of the largest corporate organizations in the country. I've seen 'em all...the good, the bad, the ugly! :-) +5

I distance myself from them as much as possible .

one word -karma- that how i deal with it

Avoid them, if they are mean I would tell them so by being assertive.

C.Y.A. always!

I completely avoid them! Don't say two words to them! Pretend they are invisible!

try to slowly send them insane by moving their things around and replacing things Amelie style.

avoid them. their actions speak for themselves...and they suffer for it.

I guess I'm lucky that I don't have co-workers like that. I seem to have a pretty good bunch of people I work with.It almost feels like a family.

I've run across that a few times. Generally, these days I handle that by firing them or transferring them someplace harmless. (One of the advantages of being the boss.)

I work with a bunch of them. There is a small group of shit talkers here that are protected by a certain manager. For three years now they have ran around, slandering everybodys name, stirring up controversey, and not taking any responsibility for it. Well, this certain manager has just given his formal resignation of April 15th. Haha, these poor folks are now in a spot of isolation. Nobody likes them, trust them, or wants anything to do with them. I haven't treated them any differently than I do the people with whom I get along with. Its better to not be sucked into their unmanagable behavior. They only make themselves look stupid and now are in between a rock and a hard place. The mature, professional, and rational people usually come out on top, usually. I'm now in a position to sit back and get the last laugh, how sweet it is.

Sarcasm. Actually I tried ALL of the suggestions offered on this question (at my former job, that it.) NONE of it worked. So, if the wages are the same, just throw the horse manure right back in their face, at least you won't be a doormat.

It depends on the situation obviously. If I'm never going to see them again, I just let it go. Better to move on. If I have to deal with them constantly, polite, assertive face to face confrontation generally spooks them and they stay away. They're a pretty spineless lot. But you have to have the skill to pull it off otherwise you just look stupid. If you don't have that skill, just politely CYA.

with apathy. try not giving them amo and avoid them when possible. other than that don't let them matter in the least bit.

ignore them, pretend like it doesn't bother you, they will stop eventually

I smile alot, keep my mouth shut as much as possible, and do my job.:)

Don't tell this co-worker anything personal about yourself that you don't want getting around. Talk to the man/woman at the top about it privately if you can. Other than that, say nothing about this. If this co-worker is that bad, enough people will (hopefully) complain that he/she will get fired. There are some people where you just don't have to say anything -- they give themselves a bad reputation!