History
Iron Man was one of the numerous heroes slaughtered by the Asgardians, who waged war against Midgard in retaliation for Odin's murder, which they believed had been committed by someone from there.
His left gauntlet was used by Agent May as a weapon when she and other S.H.I.E.L.D. agents traveled back to the past in order to prevent Odin's death.[1]