Susanoo (スサノオ; historical orthography: スサノヲ, 'Susanowo') is a kami in Japanese mythology. The younger brother of Amaterasu, goddess of the sun and mythical ancestress of the Japanese imperial line, he is a multifaceted deity with contradictory characteristics (both good and bad), being portrayed in various stories either as a wild, impetuous god associated with the sea and storms, as a heroic figure who killed a monstrous serpent, or as a local deity linked with the harvest and agriculture. Syncretic beliefs that arose after the introduction of Buddhism to Japan also saw Susanoo becoming conflated with deities of pestilence and disease.

Susanoo, alongside Amaterasu and the earthly kami Ōkuninushi (also Ōnamuchi) – depicted as either Susanoo's son or scion depending on the source – is one of the central deities of the imperial Japanese mythological cycle recorded in the Kojiki (c. 712 CE) and the Nihon Shoki (720 CE). One of the gazetteer reports (Fudoki) commissioned by the imperial court during the same period these texts were written, that of Izumo Province (modern Shimane Prefecture) in western Japan, also contains a number of short legends concerning Susanoo or his children, suggesting a connection between the god and this region.

In addition, a few other myths also hint at a connection between Susanoo and the Korean Peninsula.