9. Dum Dum Dugan
Neal McDonough plays Dugan in Captain America and reprises his role for Agent Carter. As far as where he stands in the Marvel Universe, he's a member of Fury's Howling Comandos, and in his later years gets promoted to the rank of Deputy Director of S.H.I.E.L.D.. Being that he is in his prime during the Second World War, it would be unsure of how he would fit into the series or the rest of the Marvel Universe (if at all). All the same, it would be unwise to believe Dum Dum isn't a crucial part of the organization. Certainly not afraid of doing television, the Justified and Los Angeles actor would almost certainly be up for reprising his role in a flashback. Or maybe, since Samuel L. Jackson would cost a pretty penny to show up, McDonough could slap on some make-up and play an aged Dugan in his role of Deputy Director in the present day.