Oh gosh. Well I've managed to get several people sacked. This was back in the late 80s/early 90s when I worked in a Bingo hall. Employment law wasn't anywhere near so robust as it is now but I fully maintain these fuckers deserved it.
I was the chief cash officer on site and I was besties with the guy who was my junior. Between us we covered opening hours of the whole club. At this time we had a site manager who was covering our club and another about 30 miles away. They put in a deputy manager to cover every day. He was a pile of useless wank and very quickly pissed me off by telling me I should address his as "Mr Smith" instead of "Brian". (Not real name obviously.) I kept "forgetting" and calling him Brian at which point he'd snap "Mr Smith!" and I'd say "Oh, I'm sorry." He was extremely lazy, refused to muck in and help out (we were only a small club so managers were expected to lend a hand where needed) and regularly called down from his office to have a tea brought to him (you can guess how it was made...)
Final straw was one night when I was off duty, and my bestie/office junior called me nearly in tears saying Brian the prick had basically forced him to hand over £200 from petty cash even though we had a strict policy of no loans without club manager approval. Prickface had basically told my bestie "Do it or I'll sack you". He had deliberately waited until I had left for the day before asking.
The thing was if I had reported him for that then my bestie would also have been in trouble for giving him the cash. So I bided my time as I knew I could find plenty of other things he was doing wrong.
I spent a week basically gathering evidence that only incriminated him and not anybody else, like what time he got to work, mistakes he made doing the job (this was really serious as some mistakes contravened the Gaming Act and could have led to the club being fined or even shut down) and just generally being a lazy, arrogant shit. I reported several things to the general manager but Brian the slime talked his way out of things, blaming other people or saying it was all a mistake. Fucker.
Finally he played into my hands - he asked me to lend him MORE money from petty cash, this time £2500 to buy a car. So this time I said to him "Hmm, we won't have that much cash on hand until we cash up on Friday evening, but come up to the office at 9.30 after we close and I'll sort you out."
I then called the general manager and asked him to make a "surprise" visit on Friday night. He snuck into the cash office and sat out of sight. I waited for Brian the dick to come upstairs, basically entrapped him by saying "You know it's against policy to take money from petty cash without the general manager's signature right?" He said "I don't give a shit about that, he's not here, I am." Imagine his face when the GM stood up and said "Actually I am, and you're not."
Oh it was glorious!
I also got rid of a serial sexual harasser/assaulter who used to enjoy rubbing up against the female members of staff while "just passing" behind them at the counter. He asked for a couple of day's holiday, we said no as we were short staffed. He called in sick, nobody made the connection until I spoke to one of the part timers and she told me "Hey, I bumped into Creepy McGroper at the concert - I thought he worked Saturday nights?" I immediately dobbed him in. Sacked for falsely claiming sickness. Best part was the concert was Kylie 
Put paid to another sexual harasser and genuinely dangerous-feeling bloke, you know the sort who sets your instincts screaming. He had made comments to several of the women making them feel really uncomfortable. (Again I'll point out this was the 80s/90s and the words "sexual harassment" were just a collection of syllables to most employers.) One of our employees had a mate up in court for something, and while he was waiting in the public gallery he saw Mr Creepy Fucker in the dock, charged with drunk and disorderly. It then transpired that he had two previous convictions for D&D and one for ABH. I pulled out his application form and he had failed to declare any previous convictions. Put it in front of the general manager, Creepy turned up that night for work and was sacked on the spot.
I don't feel bad about any of these, all three of them thoroughly deserved the sack. It's just that there was plenty of people working there who had done very similar, but I'd never have dobbed them in as they were good people!