Most memorable coworker? Definitely one of our devs in the first company I worked at. He was around fifty, quirky as fuck but damn knowledgeable about pretty much everything. Think some kind of uncle Iroh who could build his own compiler.
I haven't learned as much from university as I learned from our talks during smoking breaks. He never judged anyone for not knowing something (even really basic stuff) and was actually happy if he could help. Now, a few years later I still find myself applying techniques for conceptualizing software he explained to me on the balcony and I have to say I wouldn't be half the dev I am today if I'd have never met him so I guess that counts as memorable.