This is a tough one. I’m perpetual GM for most of the games I’ve played, so I never have just one character; I get to play a bunch of them. Over time, there are a few that stood out, however:
There was the hill Martian that joined the crew of a cloudship in our Space:1889 game, and who became attached to the Texan gunslinger that was being played by one of the other gamers. A generally well rounded character that has a touch of the modern “strong female character” to her. she’d be more nuanced this time around.
There was Athena — the sentient starship from our early aughties Star Trek game, and who was fun for her frustrations with her crew. One of the Treknobabble things was FTL switching for their computers. I decided that she knew the answer to questions that would be asked…but causality meant she had to wait until the question was asked to respond. If they didn’t ask it, the answer would simply dissipate in her mind. She was protective and funny, with a snarky side.
There was the troll in our Rome-based D&D game that the current game group started in. Stupid, violent, but with a weird sense of honor and morals, he was convinced with a spectacular roll by the monk to stop their fight and listen to the word of God. In a later campaign with different characters a few decades later, he turned up as a lay priest in England, where his graps of the Bible and the Ten Commandments were horribly misunderstood and he went about grifting the local passersby using the bridge by his Church with massive tolls “for God.” He was probably one of the most popular with the gaming group.
Recently, I’m rather fond of our story mcGuffin in Alien, an android named Stella. An older model that’s had her mind moved from one body to another, and has possibly been witness to some really awful stuff. She was the android with the group in the original run of the Chariots of the Gods adventure that Free League put out (and I tweaked), and she has been the impetus for adventures for a few groups now. I’ve been trying to keep her in the vein of David from Prometheus — is she sentient? Isn’t she? Does she have real feelings or is it all artifice? Does it matter?
Weirdly, now that I’m playing a single character in Fallout…I don’t think it’s as interesting as the various ones I’ve had to cough up out of nowhere and breathe life into on the fly.

