Sadako (Japanese: 貞子) aka Sadako KOL (Japanese: 貞子：咒殺 KOL) is a 2019 Japanese supernatural horror film directed by Hideo Nakata. Loosely based on the novel Tide by Koji Suzuki, the film is an installment in the Ring franchise, and a sequel to Nakata's 1999 film Ring 2. The film centers around a vengeful ghost named Sadako Yamamura who is associated with a cursed video tape; whoever watches the tape is killed seven days later.

Sadako premiered in Japan on 24 May 2019, and it played on the opening night of the Fantasia International Film Festival. A tie-in manga series, Sadako-san and Sadako-chan, was published in February before the film's release.