The surname Rai may have several origins.
Rai Sikh, members of Mahtam ethnic group who have converted to Sikh faith.Rai, a surname belonging to the Bunt community from coastal Karnataka in India.Rai (Kanji 雷, Hiragana らい) is also a Japanese surname derived from the Chinese Lei (雷)Rai dynasty (c. 416–644 CE), a Buddhist dynasty based in Sindh, in modern-day Pakistan. Sometimes it may be spelled as Ray (surname).