The Dungeons & Dragons fandom obviously like and appreciate the show for its multiple references to the game and its editions such as the monster names and overall for portraying the game in a positive light despite the stigma it got at the time (as Season 4 shows in detail). This especially felt nowadays as D&D is more popular than ever with streamers and podcasts online.
Fans of the show tend to get on quite well with fans of It (2017) due to both being stories about child characters set in the eighties and both having Finn Wolfhard in the cast. Fans of Stephen King's work in general generally love the series along with King himself, thanks to numerous references to his books from Carrie to Lisey’s Story.
Fans of Steven Spielberg and Chris Columbus' classic 80s films like E.T. the Extra-Terrestrial and The Goonies love the show for its homages to their work, especially the former, with many scenes in Season 1 referencing E.T. There's also a fair share of John Hughes fans who appreciate the nods to his teen films.
The Tim Burton fandom has come to like the show for homaging his 80s films and having Winona Ryder as one of the main leads. Season 4 in particular got appreciation for referencing Edward Scissorhands with the Eddie, Chrissy and Jason subplot (an outcast named Edward bounding with a sweet cheerleader before being hounded by her Jerk Jock boyfriend).
Fans of classic horror video game franchises such as Resident Evil and Silent Hill also tend to like the show for the very similar set-pieces, themes, locations and monster designs to said games. Some fans even wish the Duffer brothers would adapt the games themselves.
Fans of the Mother game series, especially EarthBound (1994) have come to love the show for the very similar story and themes. There's plenty of crossover fan art with the Stranger Things kids as the pixel sprites◊ from the games.
An overlap with some Supernatural fans exists, since both are paranormal/horror-themed shows with lots of references to 80s movies and shows and a classic rock/80s rock soundtrack. There's also a portion of Tumblr that enjoys drawing parallels between Mileven and Destiel. Here's a great example.
It formed one with the MonsterVerse fans mostly thanks to Millie Bobby Brown being part of both franchises as well being focused on monsters. Plus, the Mind Flayer looks very similar in appearance to the female Muto.
Many Fear Street fans are also Stranger Things fans, due to the former's films having similar throwbacks to different decades (The '90s and The '70s), Sadie Sink and Maya Hawke starring in both, and director Leigh Janiak being married to Ross Duffer.
Of course there's plenty of crossover with the Twin Peaks fandom, given they have near-identical stories. Brett Gelman even appears in one episode.
There is a bit of an Odd Friendship with Parks and Recreation. They are both complete opposites in tone but there are some similarites between Eleven and Mike and Leslie and Ben. There is a comment on this video that says:
"You know, eleven could be Leslie Knope. What are both of there favorite foods? Waffles. Doesn't Eleven's wig look a little like Leslie's hair? Also where was eleven first found? A local diner. Where can always find Leslie? A local diner. Who do they both fall in love with? A nerd that plays board games."