Zack Snyder, the director of Justice League and the Watchmen movie, dressed up as a zombified and putrid version of Luke Skywalker for Halloween.
Snyder's version of the young Luke Skywalker (played by Mark Hamill) from The Empire Strikes Back is from the brief period when Luke arrived at Cloud City, but before Darth Vader cuts off his arm. He also wields a blue lightsaber.
This is not the first time that Snyder has dressed up as Luke Skywalker: in 2017, he donned the same pressed uniform to visit his child's Halloween party at school and to distribute candy to trick or treaters. To the delight of his fans, Snyder took an impromptu picture with one of the kids, who was disguised as a tiny Darth Vader, calling the costume "Impressive, most impressive", referencing the Vader line from The Empire Strikes Back, which Darth Vader uses to try and push his son Luke Skywalker to the Dark Side.
The platform that Snyder used to share these pictures (and many behind-the-scenes ones from his movies) is Vero, a social media app that is subscription-only with a different business model from Twitter, Instagram and Facebook, and claims to be free of publicity. Its layout resembles Instagram the most, and yes, Snyder's feed is peppered with Star Wars references.