Ann Hui On-Wah (許鞍華, pinyin: Xǔ Ānhuá, born May 23, 1947) is a Hong Kong film director, one of the most critically acclaimed amongst the Hong Kong New Wave.

Hui was born in Anshan, Manchuria and she moved to Macao, then to Hong Kong when she was five. She studied English language and literature and comparative literary studies in the University of Hong Kong until 1972, when she received her Masters, before spending two years in the London International Film School. Returning to Hong Kong in 1975, she entered TVB as director, making many serials and documentaries on 16mm, helping in particularly King Hu as an assistant on television. The most notable featurette she made during this period was Boy From Vietnam (1978), which was her first film on Vietnam and formed the first of her "Vietnamese trilogy".

Hui left television in 1979, making her first feature The Secret, a mystery thriller based on real life murder case and starring Taiwanese star Sylvia Chang . It was immediately hailed as an important film in the Hong Kong New Wave. The Spooky Bunch (1981) was her take on the ghost story genre, while The Story of Woo Viet (1981) continued her Vietnamese trilogy. Hui experimented with special effects and daring angles, though her preoccupation with sensitive political and social issues would make them a feature in most of her subsequent films. Boat People (1982), the third part of her Vietnamese trilogy, is the most famous of her early films, which examines the plight of Vietnamese immigrants after the Vietnam War.

In the mid-1980s Hui continued her string of critically acclaimed works. Love in a Fallen City (1984) was based on a novel by Eileen Chang, and the two-part, ambitious wuxia adaptation of Louis Cha's first novel, The Book and the Sword was divided into The Romance of the Book and Sword (1987) and Princess Fragrance (1987). 1990 saw one of her most important works to date, the semi-autobiographical The Song of Exile, which looks into the loss of identity, disorientation and despair faced by an exiled mother and a daughter faced with clashes in culture and historicity.

After a brief hiatus in which she returned briefly to television production, Hui returned with Summer Snow (1995), about a middle-aged woman trying to cope with everyday family problems and an Alzheimer-inflicted father-in-law. Eighteen Springs (1997) reprises another Eileen Chang novel while Ordinary Heroes (1999), about Chinese and Hong Kong political activists from 1970s to the 1990s, won the Best Feature at the Golden Horse Awards.

In 2002, her July Rhapsody, the companion film to Summer Snow and about a middle-aged male teacher facing a mid-life crisis, was released to good reviews in Hong Kong and elsewhere. Her latest film, Jade Goddess of Mercy (2003), is adapted from a novel from Chinese writer Hai Yan.