The King: Eternal Monarch (Korean: 더 킹: 영원의 군주) is a 2020 romantic-fantasy South Korean television series starring Lee Min-ho, Kim Go-eun, Woo Do-hwan, Kim Kyung-nam, Jung Eun-chae, and Lee Jung-jin. Written by Kim Eun-sook and produced by Hwa&Dam Pictures and its parent company Studio Dragon, the series premiered on SBS TV and Netflix for the global audience on April 17, 2020.

Set in two parallel worlds, the series follows Emperor Lee Gon of the Kingdom of Corea, who discovers access to an alternate reality after crossing a mythical door opened by his half-uncle, Lee Lim, where the Republic of Korea exists in the Kingdom's stead and sets out to put an end to Lee Lim's atrocities and retrieve the other half of Manpasikjeok used as a portal between two worlds.

Hailing as one of the most-anticipated series in the first half of 2020 due to its ensemble cast, screenwriter, extensive publicity and production budget, the series set a record for SBS's highest 2020 Friday-Saturday drama premiere ratings. It also maintained the No.1 spot on the weekly Wavve drama chart for eight consecutive weeks, and was listed as the most popular Korean drama series on Netflix in India, Malaysia, Philippines and Singapore and one of the top two in the U.S. The series received mixed reviews and lower-than-expected domestic TV viewership ratings on later episodes, with news media attributing it to competition from streaming platforms and criticism of its screenplay, production and various controversies.