Died in the first game I played. We were captured by a bunch of female elves who wanted to enslave us, and I was inspired by the Conan books I had recently been reading to refuse to submit. The queen knocked me out with a spell, and when one of my fellow PCs also defied her, she ordered two of her soldiers to stab their spears into my throat as an object lesson. That wasn't really my own character though, since I asked the DM to run a one shot game for me, and he used characters that were playing in the game he was running so we wouldn't have to bother rolling fresh ones up.
My first actual character was a gnome fighter/mage made with 2e rules (sort of, the other players cheated a lot, since they figured the DM was a killer). We fought some skeletal knight who was willing to talk, but had decided he was going to kill us one way or other. I think he was supposed to be really tough, but the PCs got some very good rolls and managed to win. I was the only one that died, but luckily they found a scroll in the skeleton's treasure that brought me back to life. Then a little bit later, my character was standing watch while the others were resting and the wind picked up. I tried using my Weather Sense proficiency to see if a storm was coming in, when the DM blindsided me with an invisible stalker.
The first PCs death I caused was actually part of a TPK. The players invaded a goblin lair, and because they'd had a string of easy victories, they were cocky and overconfident. Then the goblin cleric cast a hold person on the party fighter, and the goblin mooks nickled and dimed him nearly to death, with a lucky crit finishing him off just after the spell wore off. After he fell, it didn't take long for the other PCs to bite it.