You is an American psychological thriller television series based on the books by Caroline Kepnes, developed by Greg Berlanti and Sera Gamble, and produced by Berlanti Productions, Alloy Entertainment, and A+E Studios in association with Warner Horizon Television, now Warner Bros. Television.

The first season, which is based on the novel You, premiered on Lifetime in September 2018, and follows Joe Goldberg, a bookstore manager and serial killer who falls in love and develops an extreme obsession. The season stars Penn Badgley, Elizabeth Lail, Luca Padovan, Zach Cherry, and Shay Mitchell. Lifetime announced in July 2018 that You had been renewed for a second season, based on Kepnes' follow-up novel Hidden Bodies. The series later moved to Netflix and the second season was released in December 2019. The season follows Joe as he moves to Los Angeles and falls in love with local heiress Love Quinn. For the second season, Ambyr Childers was upgraded to a series regular, joining newly cast Victoria Pedretti, James Scully, Jenna Ortega, and Carmela Zumbado.

In January 2020, the series was renewed for a third season by Netflix, which was released on October 15, 2021. In the third season, Saffron Burrows was upgraded to a series regular, joining newly cast Travis Van Winkle, Shalita Grant, Tati Gabrielle, and Dylan Arnold. In October 2021, ahead of the third-season premiere, the series was renewed for a fourth season, which was released over two parts on February 9 and March 9, 2023. The season also stars Charlotte Ritchie, Tilly Keeper, Amy-Leigh Hickman, Ed Speleers and Lukas Gage. In March 2023, the series was renewed for a fifth and final season.