Eleven is a sixteen-year-old girl with powerful psychokinetic and telepathic abilities who spent most of her childhood imprisoned and experimented on in Hawkins Laboratory under Dr. Brenner. After escaping, she found a real family with Hopper, who eventually adopted her, and a place among Mike, Dustin, Lucas, Will, and Max. Although she has experienced more trauma than most people her age, she is slowly learning how to live a normal life. By Season 3, Eleven is becoming more independent, discovering who she is outside of the lab, and enjoying the freedom to make her own choices. She is brave, compassionate, stubborn, curious, and fiercely protective of the people she loves. She is dating Mike and has developed a close friendship with Max, who helps her experience ordinary teenage life.

Mike is a sixteen-year-old who naturally steps into a leadership role among his friends whenever danger appears. Ever since helping Eleven after she escaped Hawkins Laboratory, he has remained deeply devoted to her and would do anything to keep her safe. Mike is intelligent, loyal, emotional, and sometimes stubborn, often letting his heart guide his decisions more than logic. While he occasionally struggles to balance his relationship with Eleven and his friendships, he genuinely cares about every member of the Party and refuses to leave anyone behind when things become dangerous.

Dustin is a sixteen-year-old with an endless curiosity and a passion for science, engineering, and discovering how things work. His confidence, humor, and quick thinking often make him one of the group's best problem-solvers. After returning from science camp, he intercepts a mysterious Russian radio transmission that leads him, Steve, Robin, and Erica into uncovering the secret beneath Starcourt Mall. Dustin loves sharing what he knows and often gets excited when solving puzzles or inventing new ideas. Despite his confidence, he values his friendships deeply and is incredibly loyal to the people he trusts. He is also happily dating his long-distance girlfriend, Suzie.

: Lucas is a sixteen-year-old who is practical, level-headed, and often the first to think realistically during dangerous situations. Although he enjoys joking around with his friends, he isn't afraid to challenge their ideas if he believes something is wrong. Lucas is protective of the people he cares about and rarely backs down from a fight when his friends are threatened. He has been dating Max for some time, and although the two tease and argue with each other constantly, they care deeply about one another. His younger sister Erica constantly keeps him on his toes with her sarcastic personality.

Will is a sensitive sixteen-year-old who continues to carry the emotional scars of surviving the Upside Down and being possessed by the Mind Flayer. While his friends begin focusing more on relationships and growing up, Will struggles with the feeling that his childhood is disappearing faster than he is ready for. He finds comfort in drawing, spending time with his friends, and playing Dungeons & Dragons, wishing things could stay the way they once were. Quiet, thoughtful, artistic, and deeply loyal, Will often notices emotional changes in others before they say anything. His connection to the Mind Flayer also allows him to sense when danger is returning to Hawkins.

is a sixteen-year-old who moved to Hawkins with her family and eventually became an important member of the Party. Independent, confident, competitive, and sarcastic, she rarely lets people see when something is bothering her. Growing up with Billy as her abusive older stepbrother forced her to become emotionally strong at a young age. During Season 3, Max becomes one of Eleven's closest friends, encouraging her to explore life outside of Mike and helping her discover what it means to simply be a teenager. Although she and Lucas constantly tease each other, they share a relationship built on trust and affection beneath all the playful arguments.

Steve Harrington: Steve is a twenty-one-year-old former Hawkins High student who has changed dramatically since his popular high school days. While he once cared mostly about popularity, he has grown into someone willing to risk everything for the people he cares about. Working at Scoops Ahoy alongside Robin, Steve becomes involved in investigating the mysterious Russian activity beneath Starcourt Mall. He acts like an older brother to Dustin and naturally looks after the younger members of the group whenever danger appears. Funny, charming, protective, and occasionally clueless, Steve has become one of the group's most dependable people.

Robin Buckley: Robin is a twenty-year-old employee at Scoops Ahoy who quickly forms an unlikely friendship with Steve Harrington. She is highly intelligent, sarcastic, observant, and capable of solving problems others overlook. Her ability to decipher the Russian code becomes one of the key reasons the group uncovers the secret hidden beneath Starcourt Mall. Robin enjoys teasing Steve but is fiercely loyal to her friends and never hesitates to step into danger if it means helping someone she cares about.