Most memorable co-worker for me is my senior dev at my first job. He is awesome. He taught me everything and he never complained even if I ask some basic things and never got irritated when I made dumb mistakes.. he just simply explained and ask not to repeat that mistake. He gave me one advice that never ever be egoistic about your code, Yes you can feel proud but don't be like I will never tell or explain to my junior ones. Cause of Him I am good mentor/trainer also :) along with developer. Thank god at my first job he was mentor.