The costume design in Stranger Things has contributed significantly in creating genuine 1980's designs for the characters' costumes, and has received critical acclaim for blending the authentic designs with the rural setting as well as referencing beloved films and shows from the 1980s. The costume designers for Stranger Things were Kimberly Adams and Malgosia Turzanska for season one and Kim Wilcox for season two.
- Kimberly Adams-Galligan – Costume designer (Chapters 1-4)
- Malgosia Turzanska – Costume designer (Chapters 3-8)
- Kim Wilcox – Costume designer (Season 2)
- Amy Parris - Costume designer (Season 3)
- Oksana Nedavniaya – Costume illustrator (uncredited)
The costume designers for the first season were Kimberly Adams for the first four episodes and Malgosia Turzanska for the remaining four. Adams has been a costume designer on Lizzie McGuire, associate costume designer on the Narnia film trilogy and assistant costume designer on The Ring and Fear and Loathing in Las Vegas. Turzanska has been a costume designer on Hell or High Water, Ain't Them Bodies Saints and Maggie’s Plan. She got the job through her friend Sarah Hindsgaul, the hair stylist on the series.
It was important to the Duffer Brothers that the characters and setting feel real, so Adams tried to be true to each character. She looked to films, catalogs, magazines, family photo albums and year books for inspiration, to tap into how the characters really lived in 1983. She focused her research on Middle America, where she found that there was a lot of leftover fashion from the 70s due to the recession, among other things. Turzanska looked for inspiration in street photography, candid family images, mail order catalogues like Sears, magazines (Seventeen magazines specifically) and actual period clothing.
Adams put together mood boards with images from her research to distinguish each character’s look, including the background characters and extras, who were dressed with the same care as the main characters. Adams said: "They are all part of the sets that create the world being filmed." Oksana Nedavniaya illustrated some of the costumes for Adams.
A stock of period clothing was built to cover the categories of characters they had to dress, including middle school, high school, town folk, agents, government workers and scientists. For the kids’ closets, they had multiples of the same costumes to be used for photo doubles and stunts, but also to take into account the rapid growth of the kids over the five months of shooting.
Adams encouraged input from the actors and the characters’ closets evolved and became more unique as they merged with the actors. Pieces of clothing were aged according to how long the designer felt the character had owned it. For example, Will’s clothing was more aged and hand me down than Mike, who got new clothes for the school year, to reflect the characters’ difference in social status.
Mood boards created for the characters and groups by Kimberly Adams, with some of the image sources identified.
Kim Wilcox, who had costume designed films like the Stronger and TV shows like Mr. Robot, came on board as the new costume designer for the second season. Since the season was moving a year later to the fall of 1984, and was also to pay homage to the films released during the timeline, she said to have looked over films for instance, Gremlins, Ghostbusters, Indiana Jones and the Temple of Doom, and The Outsiders for inspiration as well as more authenticity. Ultimately, it was the kids of middle school and high school yearbooks that drove the biggest inspiration.
Netflix offered Kim Wilcox and her team a bigger budget for the season, which gave them the opportunity to create a bigger archive of clothing. She shopped at many local shops in Atlanta and other vintage stores in Little Five Points. The team relied on "heritage brands" that still manufactured the same styles of the '80s, due to the lead kids' tendency for rapid growth in a very quick period of time. 
While the kids mostly continued wearing their signature stylish-clothes with some subtle changes to perceive their character maturity, it was Eleven whose clothes required the most alterations. As her story-line had her living sidelined with Hopper, the team had to figure out clothes which he would've brought her because she is "starting to relax and becoming more like a regular little girl". Wilcox also took input from Millie Bobby Brown for her character's punk makeover. 
Since the season also coincided with Halloween, the crews wanted an adorable group costume for the boys from Ghostbusters and so Wilcox and her team had to think about whose "costume would be more 'together' and whose would be less", implying Will's relaxed outfit compared to the precise ones of Mike, Dustin and Lucas. Moreover, for the Snow Ball dance sequence, the team had to see what was right and fitting for the boys' personality, because they were just on the edge of becoming adults and it was their first to a lot of such new things. Each of the boys' distinctive looks also hinted to their possible future character trajectory.
With the third season being set in the summer of 1985, Amy Parris was brought in the team as the new costume designer to search for colorful, bold accessories and outfits that reflected the nostalgia of the mid-80s.
For Eleven's new colorful look, Parris used a mix of vintage shirts and rented pieces, most of which were custom-built. She explained that the era's popular colorful, abstract graphic shirts, styled with suspenders would catch Eleven's attention at the Starcourt, because she'd never worn them before. "It was a chance for her to choose her own look and guide her own fashion sense," Parris added.
Regarding the costumes of the boys, she stated that each of the boys' outfits were selected in such a way to represent their growth and maturity. Mike has got a "little more mature" who wears "more solid polo shirts" and "his outfits are not as juvenile or as young-looking as Will," Parris added. Besides, she provided the reasoning behind Dustin's custom-designed "Camp Know Where" uniform and trucker hats, "In the '80s, that the so-called 'nerds' gravitated toward Weird Al and his music, so it seemed fitting that Dustin would wear that t-shirt. To complement that, we gave him the cassette tape shirt because he's starting to get into music."
|2017 Costume Designers Guild Award||Outstanding Period Television Series||Stranger Things, Series – Kimberly Adams, Malgosia Turzanska||Nominated|
|2018 Costume Designers Guild Award||Excellence in Period Television||Kim Wilcox||Nominated|
- "A Season of Stranger Style" Because. February 13, 2017.
- "Kimberly Adams #StrangerThings interviewed at 19th Costume Designers Guild Awards" Red Carpet Report on Mingle Media TV on YouTube. February 22, 2017.
- "Stranger Things - Costume Designing 1980s Nostalgia" Tyranny of Style.
- Instagram post by oksana_nedavniaya. July 28, 2016.
- "Stranger Things 2 Fashion Secrets Revealed" FASHIONISTA October 23, 2017.
- "The 'Stranger Things 2' Costume Designer Walks Us Through the Sequel's Wardrobe Clues" FASHIONISTA October 23, 2017.
- "The 'Stranger Things 3' Costumes Include Eleven's '80s Mall Rat Makeover and Steve's New Sailor Outfit" FASHIONISTA June 26, 2019.