Most memorable co-worker was a daft idiot.
this was 10 years ago - I was working as a junior in my very first job, fresh out of uni, for a very small startup. It was me, and the 3 founders, for a very long time. Then this old (45, from my perspective then..) dev was hired.
This guy had no idea how to do the job. no common sense. the code confused him. the founders confused him. I was focusing on my work - and was unable to help him much with his. His only saving grace? He was a nice guy. Really nice.
But why was he so memorable, out of all the people I ever worked with? simple. He had a short term memory problem. Could not, even if he really tried, remember what he did yesterday.... when I asked him what his issue was, he decribed his life is like a car going in reverse in a heavy fog. "I can only see a short distance backwards, with no idea where I'm going".

Startup was sold to a big company. I became a teamlead/architect. He? someone decided he should be a PM.