Hmmmm.... Where to start...
Our current problem is a guy who slacks off as much as possible. I swear that he actually puts more thought and effort into how NOT to do work than he actually does work. (He's even been spotted out in the warehouse staying in one place for 10-15 minutes at a time, when most tasks have you in each place for 1-2 minutes tops) He does juuuust enough to not get fired for not doing his work while others are running circles around him trying to pick up his slack. When he does something wrong, he refuses to learn how to do it the proper way. He makes rookie mistakes, when he's been in the office for over 6 years. His outlook is "Well, the next person in the process will catch any mistakes I make, so why should I bother making sure it's done the right way?" Don't even get me started on his paperwork... (And you would think that after 6+ years he'd be able to memorize his 8-digit employee ID number you use every week to fill out your timesheet, rather than having to pull out his wallet...)
He used to take so many extra breaks each day that he'd only be putting in a 6-hour workday. From a lunch that lasted an hour and fifteen or twenty minutes, to the 15-20 minute break in the morning, and then again in the afternoon, oh, and the extra 5-10 minutes it takes to get ready to walk out the door at precisely the moment his shift ends... In actuality we get a total of ONE hour of break time, spread out however we want to use it... One hour all at once, 15:30:15, etc. (as long as it fits into the workflow of the office. You don't take a break at the busiest time of the day) They finally put a stop to that bit of worker fraud...
At my company we have a VERY generous benefits package (though not necessarily generous pay). We accrue sick time at the rate of 1 day a month, and the max accrual is some insane amount. I like to think that I have a very strong work-ethic. I'm not sick that often (when I *do* call out sick my co-workers think I must be at death's door), which is why I have more than 11 weeks of sick time built up. I schedule my time off, and for emergency situations or last-minute time off my manager is very easy-going about us using our vacation/personal time to cover, even if it's very short-notice.
The previously-mentioned worker conveniently gets sick about once a month... (And it's almost always on a beautiful sunny day... Whoda thunk it?). And yet he can still take his entire annual vacation allotment all at once to visit family in Central America... Hmmmm.... (Funny thing is, our office runs at its most efficient during those weeks he's out. Odd....)
But MUCH WORSE than him.....
There's this other guy we had working in my office for a number of years (THANKFULLY he's gone, which I'll explain below) who slacked off, never helped anyone else out when they needed a hand, leered at the female teenage summer workers, and made it WELL known just what his personal feelings were about religion, politics, gays and the role that women should play in the workplace (i.e. none at all, their place was at home). He was unable to think logically for himself, so if there was a "traffic jam" in the warehouse and he couldn't get to where he needed to go, he was unable to figure out how to skip that location, go to the next one on his list and circle back later. He'd stand around until the location on his worklist was free (and this was sometimes 20+ minutes of standing around waiting). Management was loathe to do anything. He *finally* got fired for putting a note that essentially was a death-threat in a co-worker's mailbox...

I won't go into too much detail about that one, but suffice it to say that management and HR worked all that weekend so that first thing Monday morning he was no longer employed by our company, and was told to turn around and leave before he even got 40 steps from his car when he showed up (late, I might add)...