Nathan Curtis is one of the co-founders of EightShapes, a Washington, DC design agency. He is an expert in design systems. Both Nathan and Dan Brown, the other EightShapes co-founder have done much to help the UX community grow in their craft over the years.
As far back as Sept. 2015 Nathan began focusing on what design systems are and how designers/teams can leverage them to their fullest. At the time of this post, he has amassed some 30+ posts specifically geared to design systems on the Medium platform alone.