Stranger Things is an American television series created by the Duffer Brothers for Netflix. Produced by Monkey Massacre Productions and 21 Laps Entertainment, the first season was released on Netflix on July 15, 2016. The second and third seasons followed in October 2017 and July 2019, respectively, and the fourth season was released in two parts in May and July 2022. The fifth and final season of Stranger Things is expected to be released in 2025. The show is known for its cast of characters, plot, nostalgic tones, and mix of the horror, drama, science-fiction, mystery, and coming-of-age genres.

Set in the 1980s, the series centers on the residents of the fictional small town of Hawkins, Indiana, as they are plagued by a hostile alternate dimension known as the Upside Down, after a nearby human experimentation facility opens a gateway between Earth and the Upside Down. The ensemble cast includes Winona Ryder, David Harbour, Finn Wolfhard, Millie Bobby Brown, Gaten Matarazzo, Caleb McLaughlin, Natalia Dyer, Charlie Heaton, Cara Buono, Matthew Modine, Noah Schnapp, Sadie Sink, Joe Keery, Dacre Montgomery, Sean Astin, Paul Reiser, Maya Hawke, Priah Ferguson, Brett Gelman, Jamie Campbell Bower, Eduardo Franco, Joseph Quinn, and Amybeth McNulty.

The Duffer Brothers developed Stranger Things as a mix of investigative drama and supernatural elements portrayed with horror and childlike sensibilities, while infusing references to the popular culture of the 1980s. Several thematic and directorial elements were inspired by the works of Steven Spielberg, John Carpenter, David Lynch, Stephen King, Wes Craven and H. P. Lovecraft. They also took inspiration from experiments conducted during the Cold War and conspiracy theories involving secret government programs.

One of Netflix's flagship series, Stranger Things has attracted record viewership on the streaming platform. It has been received positively for its characterization, atmosphere, acting, soundtrack, directing, writing, and homages to 1980s films. It has received numerous nominations and awards. An animated spin-off series, developed by Eric Robles and produced by Flying Bark Productions, is in development. The series is an example of 1980s nostalgia.