David Harbour was part of Millie Bobby Brown's birthday celebrations

According to TMZ and photos which have since emerged, her co-star David was among the guests at the party.

They were also joined by fellow Stranger Things actor Jamie Campbell Bower, and other attendees included her husband Jake Bongiovi, her mother and grandparents, reality stars Whitney and Connor Leavitt, and filmmaker Shawn Levy.

David played Millie's character Eleven's guardian Jim Hopper in all five seasons of the hit Netflix sci-fi show.

Before the fifth and final season aired late last year, there had been reports she had accused him of harassment and bullying.

Although Millie hasn't directly address the claims, she previously insisted she and the 50-year-old actor are very close.

Speaking in a clip shared on Deadline's TikTok account, she said: "Of course I felt safe. I mean, we've worked together for 10 years.

"I feel safe with everyone on that set. You naturally just, you know ... you've been doing it for so long.

"We also play father and daughter, so naturally you have a closer bond than the rest, because we have had some really intense scenes together, especially in season 2..."

The Enola Holmes actress is proud of the work she's done with David on the current fifth and final season of Stranger Things.

She added: "But David and I have a great relationship. We work really closely together in the scenes and in preparing for the scenes.

"And I really am excited for everyone to see the labour of love, and hard work we put into the closure of our relationship, and what that looks like.

"And to give some of the fans, especially the Hopper and Eleven fans, those scenes that I feel, I think are gonna be quite impactful.

"But I love it. It makes me wanna bring my A-game every single time I see that I'm on the call sheet working with him because I know he's bringing it right back."

Following the report about alleged bullying allegations, Stranger Things co-creator brothers Matt and Ross Duffer were asked about the claims.

Ross told The Hollywood Reporter: "Obviously, you understand I can't get into personal on-set matters, but I will say we've been doing this for 10 years with this cast, and at this point they're family and we deeply care about them.

"So, you know, nothing matters more than just having a set where everyone feels safe and happy."