Iron Man
Robert Downey Jr. is the man behind the iron armor and one of the main characters that gave rise to phase one in the construction of the Marvel Cinematic Universe back in 2008. Not only did he play the lead character in the Iron Man trilogy and The Avengers saga, but he also appeared in The Incredible Hulk, Captain America: Civil War, and Spider-Man: Homecoming.
S.H.I.E.L.D. stands for Strategic Homeland Intervention, Enforcement, and Logistics Division,
not "Supreme Headquarters, International Espionage, Law-Enforcement Division" as is claimed here. Get it right, man...