The phrase "original gangster" refers to a person who is seen as a founding member or a pioneer in a particular gang or criminal organization. They are respected as one of the first and most influential members. Full definition
«Here I was, a 23 year old nerd, working on this website, and I got to meet one of the [Original Gangsters] of the Internet... this is one of the leaders and pioneers who worked to help make my career possible. (techpresident.com)