Deep Sea Monster Reigo (深海獣レイゴー, Shinkaijū Reigō) also known as Reigo: The Deep-Sea Monster vs. the Battleship Yamato is a 2008 independently-made Japanese tokusatsu kaiju film by Shinpei Hayashiya. Veteran artist Keita Amemiya designed the titular monster. The film's original working title was Reigo vs. Yamato (レイゴー対大和 - Reigô tai Yamatô).

The film, set in World War II, depicts the story of the real-life Japanese battleship, the Yamato, which is confronted in the Pacific Ocean by giant monsters, including the most fearsome of them all, Reigo.

The film was released on home video in the United States in 2019 under the title Reigo: King of the Sea Monsters.