Here is a list of the most memorable character’s I’ve roleplayed with, and a short description, in my words. These are not just characters that were already pre made, like Geralt would be. These are all characters that I built, and developed a specific story for, by roleplaying them.
A couple of them have pretty extensive backgrounds, so someday you may see a full story or character history, but for now, just mainly a list, for myself and any that enjoy this. I may edit it with more, as I remember them.
Josia Dragonblood - Josia was my very first memorable character, and the one that means the most to me.
He started as an AD&D character, a half elf shapechanging druid. At some point in the campaign, he vanished into another dimension. Long story as to how that happened, but suffice it to say, you know how D&D can be. 
About that time Everquest 1 came out. So I just decided to make him in EQ1, and say that is where he went when he vanished from D&D, and he washed up on the shores of Queynos. His entire roleplaying motivation in EQ1 was that he was trying to find his way home, to Tolra, the name of our land in D&D. Nowadays, I say that he ran across the Doctor, from Dr. Who, made friends with him, as the Doctor realized this was a person that had been in multiple times and dimensions, and now the Doctor just pops in and takes him to a different dimension every once in a while. He manages to make an appearance in almost every MMO I play, either as a main, or more often as an alt. Josia is chaotic good.
Aragon Ishtar - Yes, I totally ripped the name off from Aragorn in Lord of the Rings, BEFORE the movies ever came out, and just dropped the r to make it different. Aragon is a wood elf rogue, specializing in bows. He has only been played in D&D, and was my main character for years. He is chaotic neutral, so he pretty much did anything he wanted, with no conscience. It made for some very interesting roleplaying between him and the paladin of the group.
Rok Ard - Another D&D character, Rok, and his orc brother, Fok Dop, struck out on their own and joined a party of humans and elves that would take them along. This was mainly an exercise in comedy, because they pretty much acted like two dumb orcs that didnt’ have a clue, and everyone else played it straight. There were lots of laughs in these games.
I can’t remember the names at the moment of other D&D characters, probably because most of rest of my time was as the DM, so now we move to the age of computer games
Zthil - Zthil was a lizard man necromancer, that I played extensively in both EQ1 and EQ2. He survived the 500 years between the two games do to inadvertently preserving himself in an inanimate state, from a necromatic spell he was working on. Cool thing about Zthil, if you ever played EQ1, I had him mainly in a flowing black robe. When they released the action figures, one of them was a lizard man necro in a flowing black robe, that looked pretty much exactly like I had made Zthil. So this is the only character I’ve ever roleplayed, that I have an action figure of.
Bliz Kreeg - Bliz was the primary “evil side” character I played in EQ1. He was head of security for a dark elf guild named House Kenafin. He was a troll shadowkight, if I’m not mistaken. Its been a while.
Luse Malache - Another character I totally ripped of the name, this time without changing anything. If you have ever read the comic book Poison Elves, you will recognize this. My Luse was a dark elf illusionist. I basically just used him to run around and illusion himself as other races, and cause roleplaying havok.
Josianna Dragonblood - I played Josianna as an alt in EQ2. I could not figure out a viable way I liked to get Josia from EQ1 to EQ2, like I did with Zthil, so I just made one of his ancestors.
Aria Moryet - This is probably my second favorite character of all, next to Josia. Her formal title is Lady Aria of Kildaire. She started as an alt in Dark Age of Camelot, a blood magic sorceress from Kildare, Ireland, that had ventured to the legendary land of Camelot. She was lawful evil, basically had a thirst for power and control, but always working behind the scenes. Think, someone like Melisandre, or someone from the Illuminati, or something like that. Aria, being a sorceress, managed to cast a spell on herself that granted immortality. So I play her in many games and MMOs, but unlike Josia, she stays in this dimension. She has appeared in Pirates of the Burning Sea, and most recently, in The Secret World, helping the Illuminati, of course.
Chenesil Saracen - Chenesil was my main in Dark Age of Camelot. He was a rogue assassin. Basically, DAoC was a PVP game, so although I did roleplay Chenesil, his main purpose was for me to have a way to go PVP, by myself, and survive.
Cieasan - another character I remember from Dark Age of Camelot, he was a Hibernian Firbolg. Although I roleplayed him a lot, I don’t remember a lot about him, except for the guild he was in. It was a lot of day to day roleplaying, nothing really memorable or earth shattering.
Gnart the Gnome - Gnart was an especially fun character, although short lived. I played him in the game Horizons. GREAT game, but it fell to poor business practices and bad management. Seriously, this game could have been bigger than WoW, if they had not screwed it up in real life, it was certainly more fun when they started. Anyway, Gnart was a sorceror, in chaos magic. It was really fun to play, because every spell from the chaos line, had multiple random outcomes and you never knew when you cast exactly what would happen.
Kildaria - Ok, Kildaria comes from Aria Moryet. In my universe, Aria, in her zeal to be in power everywhere, and immortal, tried a spell, to make versions of herself in every dimension. Kildaria is the result of that. There is a Kildaria in every dimension, that has no knowledge of the other ones. She looks slightly like Aria, but does not necessarily act like her. Kildaria is a bit more fun loving, and more chaotic, with less of a thirst for pure power. Kildaria shows up as an alt or main in any game that I want to make a good looking girl, because I have the basic template, and backstory made now. WoW, GTAV, and Black Desert Online are the big ones that come to mind.
Ivee - Ivee was an alt that I made in WoW to play with a character that my wife made, because she doesn’t game very much, if at all. I ended up playing Ivee all the way to high level, and she ended up with a really great story, inadvertently, simply by roleplaying.
3.14159 - I love the story of this character. She was my main in City of Heroes. She was whatever the crowd control character was called in that game, the one with mental powers. Look at the name closely, she was in a guild called Pies Like Us. 
But I played her, wrote the whole story that explained her name, and how she got her super powers, and it remains one of my favorite character histories that I have ever written.
Whipcream - I made her specifically in City of Villians to be a nemesis for Pi. She had stark white skin. Never really played her much, I just mention her because it was such a great story in City of Heroes/Villians.
I’ve had many many other characters, these are just some of the major, or more memorable ones I have had over the years, and just thought I’d reminisce a little and share them.