Stranger Things cast look seriously grown up in behind-the-scenes pics from Netflix’s season 4

THE Stranger Things cast have been spotted looking seriously grown up in behind-the-scenes snaps from Netflix's new season.

The iconic group posed for a number of disposable-style snaps taken by Eleven star Millie Bobby Brown and shared to her Instagram.

Millie, 18, who rose to fame on the hit sci-fi show back in 2016, could be seen posing with her co-stars as they filmed for the season four.

One snap saw her dressed in 80s garb, with her hair permed, as she stuck a silly pose with Will Byers actor Noah Schnapp.

While in a second the pair were joined by Finn Wolfhard, who plays Mike Wheeler in the series, as they filmed in the back of a van.

In a third, Jonathan Byers actor Charlie Heaton joined the group as they sat in their hair and make-up chairs ahead of a scene.

New star Eduardo Franco, who has joined the cast this year as latest character Argyle, could also be seen in the background.

While a final snap saw Natalia Dyer, who plays Nancy Wheeler, and Caleb McLaughlin, who plays Lucas Sinclair, sitting on the floor.

The cast looked all grown up compared to how they were first seen in the series five years ago as young children.

"So many giggles! So much hard work! We hope you like it," Millie captioned the post, alongside a heart emoji.

It comes as Stranger Things season four was released to Neftlix today, with fans in shock at how much the stars' had grown.

After a two-year hiatus, a new threat from the Upside Down emerges, and Joe Keery's Steve, Natalia Dyer's Nancy and Maya Hawke's Robin must stop it once and for all.

However, those who have already raced through the new episodes have taken to Twitter to comment on how grown up the once young actors are now.

Alongside an array of shocked-face emojis, one person penned: "Can't believe they kept Stranger Things away from us that long! Everyone looks old as f***!"

Echoing their comments, someone else said: "Why do all of the high school kids look so old? They really tried to make it feel like the 80s as much as possible."

While a third remarked: "Well, that was a mind-blowing few episodes. On another note, they all look so grown up now!"

The fourth season of Stranger Things will be broken up into two different parts.

Therefore, there will be two different premiere dates, a separate date for each part.