Yau Nai-hoi (Chinese: 游乃海; pinyin: You Naihai) is a Hong Kong filmmaker.
He is best known as a frequent screenwriter for films produced by the independent Hong Kong production company Milkyway Image, notably films directed by Johnnie To and Wai Ka-Fai.
Yau often collaborates with fellow Milkyway Image writers Wai Ka-Fai, Szeto Kam-Yuen, Au Kin-Yee and Yip Tin-Shing.
His directorial debut arrived with the 2007 film Eye in the Sky.