Spoiler Warning: The following contains spoilers for Stranger Things Season 4 Volume 1.
Between Mike Wheeler's Dungeons and Dragons party, the older teens that help them, and Eleven, there's a pretty large group of main characters in Stranger Things already. The series is clearly an impressive ensemble show. As is the case with any ensemble series though, some of those characters are truly main characters, while others are recurring.
Many of the recurring characters in Stranger Things are so fully formed, despite less screen time, that they could easily lead their own series. These Stranger Things characters are the heroes of their own stories.
Erica
From Erica's brief introduction making fun of her brother in Season 2 to being someone in the know about the extent of the Upside Down in Season 4, Erica has come a long way. She's not a true member of the party though as she's only ever brought into the action at the eleventh hour.
Erica is just as smart as her brother, even though she's four years younger than him. She's got great comedic timing, sarcasm for days, and definitely doesn't suffer fools. Erica's story, of a tween just trying to get through her day when her brother and his friends drag her into some shenanigans, would make for a good time.
Murray
When the audience first meets Murray Bauman, he's spouting conspiracy theories at Jim Hopper and his deputies that are just a turn away from the truth. He's eccentric, to be sure, but he also leads a pretty fascinating life.
He's an investigator, not unlike Nancy Wheeler, and despite plenty of other characters finding him a little strange, he's one of the most intelligent people in Stranger Things. He's learned multiple languages, codes, and even taken karate lessons. His journey of being prepared for anything could be its own show.
Dr. Brenner
From the very first season of Stranger Things, the audience is on Eleven's side, which is why Dr. Brenner is seen as a villain. He's got some questionable practices considering he literally kidnaps children to perform experiments on, but there's no denying he's a commanding presence in the story.
Just how Dr. Brenner got into his field, whether he's always been the bad guy, and just how he keeps surviving encounters with the supernatural, are all stories the audience would love to understand.
Kali
The divergence from the main story in Season 2 to have Eleven meet her sister in Eight wasn't well received by fans at the time. That's largely because it meant that Eleven was far from the party back in Hawkins. It did bring Kali, who is a great leader and a fascinating presence, into the minds of fans though.
Kali manages to escape the lab at Hawkins before the gate to the Upside Down is ever opened. Her escape and her powers differing from Eleven's certainly leaves the audience wondering about the other children that might have survived their experiences in the lab. Kali is out living her life on her own terms, using her abilities to survive, but also to seek revenge on people who have wronged those she cares about, and her story deserves to be told.
Mrs. Wheeler
Karen Wheeler is a housewife raising three children who rarely seem to listen to her. Despite that, she still offers up advice to them and seems to know when one of them isn't telling her the truth.
Mrs. Wheeler, as Nancy notes in season 1, likely married for the security of her husband's well-paying job, and she doesn't seem particularly happy in her relationship, no matter how much she loves her children. Her ability to either command attention from her peers or blend into a crowd speaks of a woman who is always examining her options. The audience would love to know more about her.
Jason
Introduced in the fourth season of Stranger Things, Jason is the new big man on campus at Hawkins High. He's ready to lead the basketball team to victory, but more than that, he's also someone who is determined to do the right thing, even if he doesn't always go about it the right way.
Jason is stubborn and righteous and incredibly determined to get justice, and just what led him to the point of being able to rally a whole town around him as a teenager would certainly make for an interesting story.
Suzie
Dustin's girlfriend from summer camp, Suzie has only appeared in a handful of scenes. She, however, is fascinating.
Suzie is from a large family that is very religious, giving her a very sheltered life. She also has a deep love for fantasy movies and her studies, and knows how to hack her way into any 1980s computer system. There are so many small pieces of Suzie's life given to the audience already that seeing more of it would be a treat.
Robin
Robin is more of a recurring character than a side character since she's appeared in almost every episode since she debuted in Season 3. Not a member of the original party, however, it's hard to turly see her as a main character - especially since most of her storylines revolve around her connection to Steve and his connection to Mike Wheeler and his friends.
Robin talks a mile a minute, is a fast learner and is hiding a big part of herself from most of the people she knows. She's got all the main character energy someone could possibly have.
Argyle
Jonathan's new friend in Season 4 comes with a distinctive song, a cloud of smoke, and a pizza in 30 minutes or less. Argyle is also all heart. He's there whenever Jonathan needs him, even if it means he's driving Jonathan, his little brother, and their friend along with an injured government agent away from a gunfight.
Argyle is so distinct from any of the characters the audience has known from Hawkins that he could easily lead his own cast of characters through the California life of the '80s.
Eddie
Yet another character introduced in Season 4, Eddie spends a good chunk of his time hiding out from the authorities and his classmates when everyone thinks he murdered someone. The audience doesn't get a chance to get to know him beyond his rocker image and his enjoyment of Dungeons and Dragons.
Eddie exudes confidence in most situations, but he also knows he's rarely the smartest person in the room. Eddie knows who he is, and he isn't ashamed of that, which would make him an excellent main character.