Don Cheadle as James "Rhodey" Rhodes / Iron Man: A former officer in the Air Force and one of the co-CEOs of Stark Industries.
Beth Hoyt as Pepper Potts / Iron Woman: Tony Stark's former assistant, Rhodes' girlfriend, and one of the co-CEOs of Stark Industries.
Jon Favreau as Happy Hogan / War Machine: An officer in the Air Force, who pilots one of Rhodes' suits and Stark's former chauffeur and bodyguard.
Lake Bell as Natasha Romanoff / Black Widow: An undercover spy for S.H.I.E.L.D. posing as Rhodes and Potts' new assistant.
Sam Rockwell as Justin Hammer: A rival weapons manufacturer. Rockwell reprises his role from previous MCU media.
Mickey Rourke as Ivan Vanko / Whiplash: A Russian physicist and ex-convict who builds a pair of arc reactor-based electric whips to exact vengeance on the Stark family. Rourke reprises his role from Iron Man 2 (2010).
Samuel L. Jackson as Nick Fury: The director of S.H.I.E.L.D. working with Romanoff, Rhodes, and Potts.
Walt Hadfield: A former architect and Rhodes and Potts' bodyguard and chauffeur.
Clark Gregg as Phil Coulson: An agent of S.H.I.E.L.D. working under Fury.
Leslie Bibb as Christine Everhart: A reporter for Vanity Fair who has history with Stark Industries who has a brief fling with Hammer.
John Slattery as Howard Stark: Tony Stark's father and a former weapons contractor, who is a founder of S.H.I.E.L.D. and who worked on the Manhattan Project. Slattery reprises his role from previous MCU media.
Garry Shandling as Stern: A U.S. Senator, who wants to take control of the Iron Man suit. Shandling reprises his role from previous MCU media.
Paul Bettany as J.A.R.V.I.S.: Rhodes and Potts' artificial intelligence (A.I.) system who guides their suits.
Olivia Munn as Chess Roberts: A reporter covering the Stark Expo.
Yevgeni Lazarev as Anton Vanko: A former Stark Industries employee and Soviet engineer, who previously worked on the Arc Reactor with Howard Stark. Lazarev reprises his role from Iron Man 2 (2010).
Kate Mara as a process server: A process server who gives Rhodes and Potts a subpoena. Mara reprises her role from Iron Man 2 (2010).
Stan Lee as himself: An attendee at the Stark Expo, who is mistaken for Larry King.
Christiane Amanpour as herself: A news anchor for CNN. Amanpour reprises her toes from Iron Man 2 (2010).
Bill O'Reilly as himself: A political commentator for CNN. O'Reilly reprises his role from Iron Man 2 (2010).
Elon Musk as himself: The CEO of Tesla Motors. Musk reprises his role from Iron Man 2 (2010).
Larry Ellison as himself: The CEO of Oracle Corporation. Ellison reprises his role from Iron Man 2 (2010).
Peter Parker: A young Iron Man and Iron Woman fan who Rhodes and Potts save.
Tom Hiddleston as Loki: The God of Mischief and Thor's adopted brother, based on the Norse mythological deity of the same name. Hiddleston reprises his role from previous MCU media.
Stellan Skarsgård as Dr. Erik Selvig: An astrophysicist and ally of Thor who was asked to study the Tesseract. Skarsgård reprises his role from previous MCU media.
Josh Keaton as Steve Rogers / Captain America: A World War II veteran, who was subjected to an experimental super-soldier serum that enhanced him to the point of human peak physicality who was frozen in suspended animation before waking up in the modern day.