Jamie Campbell Bower sought inspiration from cult leaders for his performance in Stranger Things

He told Variety: "Jim Jones was an early reference for me.

"He was on the mood board, even with regard to certain things that he's saying when the kids are all in front of him.

"There were points where I thought, 'Do I say the word 'you' or do I use the word 'we'? We're a family now.' That's really grim!

"It totally can remove the idea of autonomy, so definitely there had to be that level of cult leader-esqueness about him."

While Mr. WhatsIt isn't as sinister-looking as Vecna, Jamie admitted his latest character was just as "terrifying" to play, particularly when working with the child actors he has taken and having to hide his true intentions and past experiences as Henry Creel.

He said: "There was so much fear in playing that.

"What you saw in Season 4 happened, and it was real.

"This is very much like, how nice can I be to these poor children to make them feel as comfortable as possible in this world? And how much of my experience am I burying within that?

"And it's always a really terrifying prospect when you're sat opposite another actor, and your intentions are so deeply buried.

"There's a level of real dishonesty in that, and that's really scary. It's really hard, particularly opposite a child."

Jamie insisted there is still a level of humanity buried within Vecna and his alter egos.

He said: "There's definitely a humanity that I can see. How much of that is portrayed in this volume is open for discussion and interpretation - there's definitely trauma and experience that is present but unexplored at this point."

The final episode of the show will be released on 31 December and Jamie insisted fans are "probably wrong" if they think they know what will happen.

He teased: "The end of seven is an incredible setup for what is to come. And if you think you know what is to come at the beginning of eight, you're probably wrong.

"It really does blow the f*** up. Whatever you think you know will be exceeded."