(All of which have been cited by show creators
Vecna lives in the Upside Down and preys on people's past traumas and guilt. The monster curses its victims, making them relive their trauma in progressively more gruesome ways until it violently kills them. (And we mean, like, really violently.)
While intending to get his revenge on Eleven and Brenner, Vecna also goes after victims who have dealt with traumatizing experiences in the past (reminiscent of his childhood and his time at the Hawkins lab).
While the character's history has changed a little bit throughout the years, he was originally a sorcerer, and after his mother was executed by the government, Vecna swore revenge. He mastered the dark arts, became a lich (an undead magician), and killed a whole lot of people.
As she reads him the letter she wrote, she falls into Vecna's trance. Steve, Lucas, and Dustin figure out that the way to save people from Vecna's curse is to play their favorite song. The song that saved Max was her favorite song, “Running Up That Hill” by Kate Bush.
At his empire's height, Vecna was betrayed and destroyed by his most trusted lieutenant, a vampire called Kas the Bloody-Handed, using a magical sword that Vecna himself had crafted for him, now known as the Sword of Kas.
While caught in Vecna's grip, a tear in the dark dimension reveals her friends on the other side, desperately trying to save her from Vecna's curse. Of course, it's "Running Up That Hill," blasted into Max's headphones that breaks Vecna's hold on her.
Vecna's Hand
This is a reference to the D&D character Vecna, for whom this Vecna is named; the D&D Vecna has a monstrous hand infused with dark magic. The design of Vecna's hand is also a nod to Freddy Krueger, the Nightmare on Elm Street villain who had a huge influence on this season in general.
There are still a few details we don't know, but it's clear that Brenner secretly kept Henry around as an orderly and the chip in his neck was some kind of power suppressant. Without it, Henry is able to unleash his powers on those in the lab, slaughtering nearly everyone, including the children.
School newspaper reporter Fred Benson (Logan Riley Bruner) fled from a deadly car accident that continues to haunt him. Patrick was targeted due to his father's abuse of him. Finally, Vecna targets Max for her trauma from witnessing Billy's death and uses Barb's (Shannon Purser) death as a way to use Nancy.
Clocks represent a passing of time, which can represent the fact that Vecna's victims' time has nearly run out — it is no coincidence that many of the clocks are set to midnight. Throughout the series, we learn that Vecna is a human who found himself trapped in the Upside Down for years thanks to our girl, Eleven.
While falling into the dark dimension, One/Henry is struck by lightning, disfiguring him.
Vecna's use of his victims' guilty conscious to terrorize his prey is an obvious tool in his arsenal. What is more subtle and powerful is that he uses shame to isolate and control.
For all his power, Vecna couldn't escape his own mortality. He began to fear death and take steps to prevent his end from ever coming about.
This is because his trusted accomplice, Kas the Bloody-Handed, betrayed him and used the sword Vecna created himself to chop off his left hand and remove his left eye. This ultimately destroyed Vecna. Though they're clouded with cataracts, Vecna in Stranger Things has both of his eyes. For now, at least.
Played by Jamie Campbell Bower, each prosthetic was glued to his skin with medical adhesive by prosthetics designer Barrie Gower and his team. For the finishing touch, Vecna was covered in "glossy slime to make him really, really glossy and wet looking," according to Gower.
The orderly, who befriended Eleven because she was the most powerful subject, tricks her into removing a chip in his skin. It turns out that the orderly is the mysterious Number One, a man named Henry Creel who came under Brenner's care after killing his parents.
He gets punished with electrocution after telling Eleven that Dr. Brenner lied to her about her mother dying during childbirth. He's smart enough to use an ostensibly harmless game of chess with Eleven to inform her Dr.
One manipulated Eleven into plotting her own escape, which also involved getting her to remove the device in his neck. (Henry, however, did not tell Eleven the truth when he said Brenner wanted her dead.
After inflicting protracted suffering, Vecna finally executes the victim, using his powers to make them levitate before snapping their limbs and gouging out their eyes.
Music evokes strong memories that are both good and bad, so it makes sense that it could open a doorway out of the oppressive alienation of trauma, despair, and guilt that Max found herself in.
In episode 7, Vecna is revealed to be Henry Creel (played as a youngster by Raphael Luce), the son of Victor Creel (Robert Englund) and his wife Virginia (Tyner Rushing) shown in the 1950s flashbacks.
Physically, yes. Lucas tells his friends that Max is in a coma, and we see her wearing casts on her arms and legs. The Duffer brothers have also confirmed that at the end of Season 4, Max is alive yet "brain dead, blind, and all of her bones are broken." The big mystery is where the redhead is mentally.
In the Upside Down, Eleven is being restrained by Vecna's vines while he attempts to kill Max, breaking her legs and arms before he begins to take her eyes.
The fan-favorite character ended the season in a coma with her bones broken and eyes blinded at the hands of Vecna. Max technically died for one whole minute before Eleven revived her friend, but Eleven's powers weren't enough to bring Max fully back to life.