Mike McGill as General Thaddeus Ross / Red Hulk: Betty's father and a U.S. Army general who has dedicated himself to capturing the Hulk who injects himself with various serums that transports himself into a red version of the Hulk.

Tim Roth as Emil Blonsky: A Russian-born officer in the United Kingdom's Royal Marines Commandos who takes over Ross' position after he goes rogue. Roth reprises his role from previous MCU media.

Mark Ruffalo as Dr. Bruce Banner / Hulk: A nuclear physicist and biochemist at Culver University who, because of exposure to gamma radiation, transforms into an enormous green humanoid monster when enraged or agitated.

Liv Tyler as Dr. Betty Ross: A cellular biologist and Bruce's former girlfriend, from whom he is separated as a result of his condition. Tyler reprises her role from previous MCU media.

Tim Blake Nelson as Dr. Samuel Sterns: The cellular biologist who develops a possible antidote to Banner's condition. Nelson reprises his role from previous MCU media.

Ty Burrell as Leonard Samson: A psychiatrist who is in a relationship with Betty during Bruce's absence. Burrell reprises his role from The Incredible Hulk (2008).

Christina Cabot as Kathleen Sparr: A major who is Thaddeus Ross's personal aide. Cabot reprises her role from The Incredible Hulk (2008).

Mark Wingert as Tony Stark: A billionaire who escaped captivity in Afghanistan with a suit of armor he created and a consultant for S.H.I.E.L.D.

Clark Gregg as Phil Coulson: An agent of S.H.I.E.L.D.

Stellan Skarsgård as Dr. Erik Selvig: An astrophysicist formerly working with Foster and Thor.

Samuel L. Jackson as Nick Fury: The director of S.H.I.E.L.D., studying the Tesseract's energy and monitoring superhuman activity.

Tom Hiddleston as Loki: Thor's estranged adopted brother and former prince of Asgard and crown king of Jotunheim, based on the Norse mythological deity of the same name.

Josh Keaton as Steve Rogers / Captain America: A World War II veteran enhanced to the point of peak human physicality by an experimental serum who was recently revived after being frozen in suspended animation for the past 70 years.

Chris Hemsworth as Thor: An Avenger, Loki's estranged adopted brother, and crown prince of Asgard, based on the Norse mythological deity of the same name.

Jeremy Renner as Clint Barton / Hawkeye: A master archer and Avenger working as an agent for S.H.I.E.L.D.

Lake Bell as Natasha Romanoff / Black Widow: A highly trained spy and Avenger working for S.H.I.E.L.D.

Alex Denisof as The Other: Thanos' vizier.

Josh Brolin as Thanos: The Other's master, who is looking for the Infinity Stones.

Ophelia Lovibond as Carina: Tivan's slave.

Ray Stevenson as Volstagg: A member of the Warriors Three, a group of three Asgardian adventurers who are among Thor's closest comrades, known for both his hearty appetite and wide girth.

Jaimie Alexander as Lady Sif: An Asgardian warrior, Thor's childhood friend and Foster's romantic rival, based on the deity of the same name.

Benicio del Toro as Taneleer Tivan / The Collector: An obsessive keeper of the largest collection of interstellar fauna, relics, and species in the galaxy who operates out of a place in space named Knowhere.

Natalie Portman as Jane Foster: An astrophysicist and Thor's girlfriend, who studies the phenomenon of the Bifröst.

Kat Dennings as Darcy Lewis: Jane's intern who is studying political science.

Thomas Kretschmann as Baron Wolfgang von Strucker: The leader of Hydra in Sokovia.

Henry Goodman as Dr. List: Strucker's partner and a scientist for Hydra and an expert in computer robotics, alien technology, enhancement, and human experimentation.

Pietro Maximoff: A Sokovian native and volunteer for Hydra who gained superhuman speed and metabolism.

Wanda Maximoff: A Sokovian native and volunteer for Hydra whose witch abilities were greatly amplified, giving her telekinesis, hypnosis, and chaos magic.

Bucky Barnes / Winter Soldier: Rogers' childhood best friend who has re-emerged as an enhanced brainwashed assassin after supposedly being killed in action during World War II.

Seth Green as Howard the Duck: An anthropomorphic duck living in Tivan's archive.

Cosmo the Spacedog: An anthropomorphic dog who the Soviets sent to space in 1962.

Michael Douglas as Hank Pym: A former S.H.I.E.L.D. agent, entomologist, and physicist who became the original Ant-Man in 1963 after discovering the subatomic particles that make the transformation possible.

Evangeline Lilly as Hope van Dyne: Hank and Janet van Dyne's daughter who takes on the Wasp mantle.

Anthony Mackie as Sam Wilson / Falcon: An Avenger allied with Rogers and a former pararescueman trained by the military in aerial combat using a specially designed wing pack.