Stranger Things star David Harbour has officiated a fan's wedding after vowing he would do so if he got 125,000 retweets.

The 42-year-old actor, who plays Jim Hopper in the popular web television series, set the challenge in January after an avid fan shared a message on Twitter asking: "What would it take to get @DavidKHarbour to be the Officiant at my wedding in September?!"

Taking the tweet in good spirits, Harbour said he would get ordained and oversee the ceremony as long as the nuptials worked with him filming the third season of the much-loved hit Netflix show.

"125k retweets," he tweeted.

"Provided date works with s3 shooting schedule, I will get ordained and perform ceremony.

"I get to read an esteemed love letter of my choosing, and after the cake is officially cut, I get the very first piece. #allthecakes."

David Harbour with the cast of Netflix's Stranger Things

Fast forward seven months, and Harbour, with the help of Twitter made Erika and her fiancé's dream come true on their big day.

Over the weekend, Harbour shared a picture on Twitter which shows him at the wedding, dressed in character as Chief Hopper.

"Hey internet," he wrote.

"I know it's been awhile. I retreated. Needed some space. You probably get it. But I've been thinking about ya in the interim. And all your retweets.

"And so me and some fun folks in Springfield, Illinois made good on our promise we made all those months ago."

Stranger Things will return for a season three summer 2019.

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