The Marvel Cinematic Universe is filled with superheroes who put their lives on the line to save the world, though they aren't always on their own. There have been a number of popular side characters introduced who have helped develop the successful shared cinematic universe in various ways.
Former side characters like Pepper Potts, Agent Coulson, or Maria Hill have moved on to main roles in the MCU or even heroic members of the Avengers. There are still quite a few who have become fan-favorites over the years due to their unique personalities and helpful abilities that have made them stars in their own right.
10 Harley Keener Is An Inventive & Street Smart Young Friend Of Tony Stark
2013's Iron Man 3 introduced young Harley Keener, an inventive boy with the attitude to match Tony Stark's. Harley helped him investigate one of the Mandarin's "bombings" that led to the reveal of Aldrich Killian and his A.I.M. organization's involvement.
Keener helped get Tony Stark back on his feet without giving him any slack for who he was, creating a close friendship that Stark later rewarded with a garage full of tech. Keener hasn't been seen much in the MCU, though he returned for Stark's funeral after his sacrifice in 2019's Avengers: Endgame, which at least referenced his relationship with Harley.
9 Katy Is A Skilled Archer & Driver Who Has Mastered The Art Of Confusion
2021's Shang-Chi And The Legend of the Ten Rings brought a new mystical hero into the Avengers' ranks, though Shang-Chi wasn't alone. He was joined by his closest friend, Katy, his fellow valet who discovered a unique talent for archery after they traveled to the legendary city of Ta Lo.
Katy is a hilarious ally with a captivating character arc that made her an instant hit among MCU fans. However, she has also mastered the hilarious "art of confusion," which was seen when she tried to distract assassins by randomly singing "Hotel California" by The Eagles.
8 Korg Is One Of Thor's Fellow Sakaarian Champions With A Unique Personality
The alien Kronan warrior named Korg was trapped on Sakaar along with Thor and Hulk in 2017's Thor: Ragnarok after he attempted to lead a rebellion against the Grandmaster, but didn't print enough pamphlets to inspire a revolution.
Korg has a unique personality that contrasts with his strong and jagged rocky build, but it has made him a loyal ally of Thor as well as a fan-favorite character who has made a few follow-up appearances since his debut alongside his insectoid ally Miek.
7 The Howling Commandoes Were Captain America's Team During World War II
2011's Captain America: The First Avenger also introduced the side character of Bucky Barnes, who later appeared as the Winter Soldier in the following phases of the MCU before going on to star in his own Disney+ series.
However, he wasn't the only ally of Captain America who helped fight Hydra during World War II. A team of international soldiers that included Dum Dum Dugan and James Farnsworth/Union Jack became known as the Howling Commandoes after they joined Captain America, leading to a number of fun callbacks over the years.
6 Jimmy Woo Is A Wholesome & Hilarious FBI Agent With A Big MCU Future
Agent Jimmy Woo didn't appear in the MCU until after S.H.I.E.L.D.'s fall, though he was able to find a new career with the FBI where he first came into contact with the Avengers as Scott Lang/Ant-Man's handler.
Woo would later return in WandaVision to help the town of Westview with a series of missing person cases that saw him work alongside S.W.O.R.D. to potentially set up a larger future for the kind and comedic special agent in the MCU.
5 Ned Leeds Is Spider-Man's Best Friend Who Operates As His "Guy In The Chair"
Peter Parker is leading the later phases of the MCU as Spider-Man after his debut led to a close mentorship with Tony Stark/Iron Man. However, Peter is aided by his best friend from high school Ned Leeds, who quickly found a use for himself as Spider-Man's "guy in the chair."
Ned has a hopeful attitude and a youthful excitement for his best friend's adventures which corresponds with the fandom's own love for the character. Ned Leeds also has a potential dark turn in store which has fans watching the character closely as the next phases of the MCU develop.
4 Darcy Lewis Found New Fame In WandaVision After Her Debut In 2011's Thor
When Darcy Lewis first appeared in 2011's Thor, she was a political science intern working with Jane Foster to explore the theories that led them to Asgard's discovery. Lewis became an early fan favorite due to her sarcastic sense of humor and relatable observations.
Lewis would return as an astrophysics Ph.D. in WandaVision on Disney+, where she would become an integral part of the investigation into Westview that saw her team-up with heroes like Vision, alongside Agent Jimmy Woo and S.W.O.R.D. agent Monica Rambeau. Lewis won over a number of MCU fans, and she'll likely return to help even more heroes.
3 Luis Became A Fan-Favorite Character Known For His Quick Recap Skills
2015's Ant-Man followed Scott Lang as he took on a heist for Hank Pym in order to protect his size-changing Pym Particle tech from being used as a weapon for the government. Luis is Lang's closest friend and a member of his heist crew-turned-security consultants.
Luis has a unique ability to artfully recap events and tell stories that quickly made him stand out among other side characters, which has fans hoping to see more of him in the Ant-Man franchise and beyond.
2 Heimdall Aided Thor In Every Way Possible Before Sacrificing Himself
As Thor found his path and dealt with threats to Asgard in his own MCU franchise, he was aided at every step by the loyal Bifrost guardian, Heimdall. The all-seeing Heimdall was sworn to follow the command of Asgard's ruler, though he still proved to be a loyal ally to Thor and his friends when the throne was usurped by Loki.
Heimdall helped guide Thor to answers about the Infinity Stones and kept Asgardians safe and hidden away when Hela took over the realm in Thor Ragnarok. Heimdall's services to his king and old friend finally ended when he sacrificed the last of his power to send Hulk to Earth as a warning before he was killed by Thanos in 2018's Avengers: Infinity War.
1 Happy Hogan Has Grown With The MCU Since His Debut In 2008's Iron Man
Tony Stark first appeared alongside his driver and bodyguard Happy Hogan, who became a close friend and trusted confidante over the years as his position evolved to become head of security. However, Hogan soon found himself thrust into a new role as a mentor after Tony Stark's death left his young ally, Peter Parker/Spider-Man, adrift in a world without Avengers.
Hogan is as much a part of the foundation of the MCU as Iron Man and the other members of the Avengers and he continues to play a role long after some of those heroes have died or retired, proving he is one of the MCU's best side characters.