When it was revealed at the end of Season 3 that Coulson and co. answer to a new director of S.H.I.E.L.D. many thought it was Agent May but then a few weeks ago we found out it was actor Jason O'Mara in the role of the unknown director of S.H.I.E.L.D.
All we have to go on is that he will be an established comic book character, "whose roots go back to the 1940s." O'Mara himself dropped a extra little hint during an interview with TV Line: "It's a manly name. Yes, a very manly name."
Agents of S.H.I.E.L.D. returns Tuesday, Sept. 20, 2016 on ABC.
http://screenrant.com/agents-shield-season-4-photo-jason-omara-director/