Only myself and only twice, once was half my fault and the other time was totally my fault. It was many years ago with a group that has since disintegrated, this was in a campaign setting that is very low fantasy, iron age and gritty

The first was a warrior type character, we were rolling back story events to enrich the character and I happened to roll werewolf, for most characters this wouldn't have such a huge problem since they only hulk out during a full moon at night, with the only exception that they have a penalty to rolls against fear and fail that roll (then they would get an extra roll and if they fail that they hulk out) the paper with the back story elements even said that werewolves have to kill everything, it's not just a cool powerup, it's more like a horror movie where you kill your best friend, then your wife etc. Since I had decided prior to this werewolf discovery that my will power was going to be my weak stat (everyone had at least one weak stat, I chose will power) and since will power is used against fear I would now potentially hulk out during fearful moments. I figured you only roll against fear when you see ghosts or big scary monsters, this was a low fantasy game and you don't roll fear against human bandits.

Wrong, big time wrong. We circulated GM-responsibility and every single one wanted to do campaigns with the undead or demons. Yeah I ended up hulking out a lot. The bigger problem was that I was also the big strong warrior guy, even in my normal state none of them could stand up to me individually but when I changed into a werewolf it became a lot worse.

After 3 sessions I decided "enough is enough" and just said that my werewolf character is not coming back.

The reason I say it's only half my fault is a) I rolled it, it was not my decision to even have this list and b) I did not decide that every campaign should have big scary monsters, they could've gone with bandits but noooo.

The second one on the other hand is 100% my bad, I thought it was a cool idea, it was a cool idea, it was also a bad idea. Because this was when we finally got a dedicated Game Master and I had (I think) three character ideas to pitch to him, the cool one was the main one and then I had two backups depending on the structure of the campaign.
So the idea was that in this campaign setting there are dragons, they are very rare creatures of wonder and magic, they are also greedy and care nothing for humans. One of the races of dragons had the magical ability to shape shift and there were even stories about dragons shape shifting into humans or elves (this was all in the monster manual BTW, I'm not making any of this up).
I wanted to play as one of these dragons, this is in game cannon that you could potentially do this, I don't think it was designed to be that way though. He liked the idea and was impressed with my research but had a few caveats
a) it has to be a young dragon so I can't just start off with a thousand character points (normal is 200-300), I was able to get away with 500 which is A LOT but
b) I had to spend most of it on "useless" dragon skills like dragon language, dragon culture, so I took a huge array of esoteric skills and put only a little in combat and magic
c) I have to roleplay as a dragon, meaning vain, impulsive and greedy became my main character personality traits. He was extremely clever, strong and handsome.
I was also granted a huge amount of starting gold but since I was vain and greedy I can't trade it for useful stuff. No I had to be clad head to toe in jewelry. Pretty, shiny and useless jewelry.

Well here's the problem, I was basically playing a sociopath and the GM demanded that I don't stray from character.

It did not take many sessions before I decided this was untenable so I asked the GM if I'm allowed to "exit with style", he said "sure" with a look of morbid confusion. So my character told the rest of the party that it had been a pleasure to travel with them, he then rode a bit away into an open space and turned into a huge glorious red and green dragon, wingspan the size of a castle, maw big enough to swallow a horse whole.

Did I mention that only the GM knew it was a dragon at all? Yeah the other players were shocked and then became a bit annoyed with me.

It still makes me happy.