HAI or Hai may refer to:

• Hai (film), a 2002 Telugu film
• Hai, a 2017 Kannada film

• Hai, a variant on the Chinese Xǔ (surname) (許/许)
• Hǎi, a Chinese surname (海)
• Hoàng Hải (born 1982), Vietnamese singer
• Thanh Hải (1930–1980), Vietnamese poet
• Fawzia Saeed Hai (1942–1968), Pakistani model

• Hai Gaon (939–1038), Jewish theologian, rabbi and scholar
• Yu Hai (born 1987), Chinese footballer
• Hai Lam (footballer), Norwegian footballer
• Hai Du Lam, American League of Legends player

• Hai, Lviv Oblast (Ukrainian: Гаї), a village in Ukraine
• Hai (Ukrainian: Гай), a village in Boiany Commune, Novoselytsia Raion, Ukraine
• Hai District, Tanzania
• Hai River, China
• Haiti, IOC and UNDP code HAI

• Hai (midget submarine), a German submarine from World War II
• Hai (keelboat), a sloop-rigged one-design yacht class
• Hellenic Aerospace Industry
• Helicopter Association International
• Hemagglutination inhibition assay

• Haï, a book by Jean-Marie Gustave Le Clézio
• Hái!, a 2003 album by The Creatures
• Hai (Cantonese profanity)
• Hai (magazine), an Indonesian weekly for teenage boys
• Hai (symbol) or chai, letters of the Hebrew alphabet
• Hai! (Live in Japan), a 1982 album by Cabaret Voltaire
• Hai dialect, of West Kilimanjaro language
• Health Action International, non-profit organization based in The Netherlands
• Heterosexual Anal Intercourse, see Anal sex
• Hospital-acquired infection, or healthcare-associated infection
• Humanist Association of Ireland
• Wolfpack Hai, a wolfpack of German U-boats during World War II
• Half as Interesting, a YouTube channel hosted by Sam Denby

• Hailuoto
• Jai (disambiguation)