Oh dear, I don't think I even remember what my first creative project WAS. I think it might have been from when I was 8-9, and it was, shall we say, HEAVILY INSPIRED by Star Wars?
So, uh... I went on my old (OLD, YOU GUYS) deviant-art and some gears turned and I THINK this guy is the oldest character that I still have some recollection of. I think I was 14 when I created him. His name was Kitaro, and he was like... Let me see if I remember this. He was a teen-aged clone of some genius military (?) commander who actually had the old commander's cryogenically-preserved brain inserted into the clone body, but he didn't know this, and had like, random flashes of memories that weren't his and a woman that he remembers loving (of course), and was super moody and withdrawn and EDGY. If I remember right the original commander I think was from a futuristic warring state era who fought for FREEDOMS (of course) and lost. 500 years later, Kitaro lived in a caste-based authoritarian dictatorship that he (of course) eventually came to overthrow with his brilliant inherited mind. The dictatorship created him in the hopes of controlling his genius but they made a mistake with who his handler was, and she was actually a sekret rebel agent (of course) who eventually used his memories of HER GREAT GREAT GRANDMOTHER to manipulate him into joining the rebels. I still very much like the political/military sci-fi angle in my stories but I've moved away from edgy, teen-aged, memory-screwed clones for now, so he doesn't really have a modern-day incarnation.
However, this character may actually be older? See, I feel like he may be, because I don't actually remember what the hell his story was anymore. It some some futuristic science fantasy world with like, science and magic and a quest about memories of past lives to use in overthrowing an evil king or something. But I know for sure that I worked on this story past the story of the guy above, so I don't actually remember who came first.
THIS guy actually still exists, albeit in a very altered form. This guy was always a snarky, sarcastic jerk with hidden demons and a golden heart, and he eventually transformed into this guy.
They're not the same character but they are the same character archetype and they have similar mannerisms and tendency for social antagonism. Also they're both kinda effeminate on the outside but are actually pretty rough and masculine in terms of their actual behaviour, which I just... find fun to write.