Robert Downey Jr. Tony Stark / Iron Man Chris Hemsworth Thor Odinson Mark Ruffalo Bruce Banner / The Hulk Chris Evans Steve Rogers / Captain America Scarlett Johansson Natasha Romanoff / Black Widow Jeremy Renner Clint Barton / Hawkeye James Spader Ultron (voice) Samuel L. Jackson Nick Fury Don Cheadle James "Rhodey" Rhodes / War Machine Aaron Taylor-Johnson Pietro Maximoff / Quicksilver Elizabeth Olsen Wanda Maximoff / Scarlet Witch Paul Bettany J.A.R.V.I.S. (voice) / Vision Cobie Smulders Maria Hill Anthony Mackie Sam Wilson / Falcon Hayley Atwell Peggy Carter Idris Elba Heimdall Linda Cardellini Laura Barton Stellan Skarsgård Erik Selvig Claudia Kim Dr. Helen Cho Thomas Kretschmann Baron Wolfgang von Strucker Andy Serkis Ulysses Klaue / Klaw Julie Delpy Madame B Stan Lee Stan Lee Henry Goodman Dr. List Brian Schaeffer Strucker Mercenary Dominique Provost-Chalkley Zrinka Isaac Andrews Costel Gareth Kieran Jones Sokovian Acid Student Chan Woo Lim Dr. Cho's Assistant Minhee Yeo Dr. Cho's Assistant Bentley Kalu Klaue's Mercenary Julian Bleach Ballet Instructor Vuyo Dabula Johannesburg Cop Nondumiso Tembe Johannesburg Driver Kabelo Thai Johannesburg Onlooker Mandla Gaduka Johannesburg Onlooker Antony Acheampong Johannesburg Elevator Passenger Ingvild Deila World Hub Tech Tony Christian Sokovian SUV Driver Barry Aird Sokovian Police Captain Kerry Condon F.R.I.D.A.Y. (voice) Josh Brolin Thanos (uncredited) Lou Ferrigno Hulk (voice, uncredited)