Dr. Haing S. Ngor (Traditional Chinese: 吳漢, March 22, 1940 - February 25, 1996) was a Cambodian American physician, actor and author who is best known for winning the 1985 Academy Award for Best Supporting Actor for his performance in the movie The Killing Fields, in which he portrayed journalist and refugee Dith Pran in 1970s Cambodia, under the rule of the Khmer Rouge. His mother was Cambodian and his father was Chinese.

Haing S. Ngor was a native of Cambodia, and before the war was a physician (obstetrics) and medical officer in the Cambodian army. He became a captive of the Khmer Rouge during the and was imprisoned and tortured; in order to escape execution he denied being a doctor or having an education. He moved to the U.S. as a refugee in 1980, and though he had no formal acting experience, he was chosen to portray photographer Dith Pran in Killing Fields, The (1984) and won an Academy Award. He went on to a modestly distinguished acting career, while continuing to work with human rights organizations in Cambodia on improving the conditions in resettlement camps, as well as attempting to bring the perpetrators of the Cambodian massacre to justice. On 25 February 1996, Ngor was found shot to death in the garage of his apartment building in Los Angeles. Relatives and friends speculated that the killing was revenge for his opposition to the Khmer Rouge.

Haing Ngor was a doctor by training. As a Buddhist, he examined his life according to principals of the cycle of life, each reincarnation a part of the struggle to perfection. He was captured by the Khmer Rouge following the 1975 takeover of Cambodia by that party, and endured 4 years of torture and starvation. He had to conceal his medical training to escape execution, even to the extent of being unable to offer medical help when his wife and child died in a difficult premature labor. At the time of the Vietnamese invasion he, along with his orphaned niece Ngim whose parents were slain by the Khmer Rouge, escaped to a refugee camp in Thailand, and they emigrated to the United States in 1980. He always specified his intention to adopt Ngim (Sophia) but in fact never did so. In February of 1996, after surviving the Killing Fields of Cambodia, he was shot while standing near his BMW in the driveway of his home. At first it was thought that he was killed by Khmer Rouge agents, but police investigation found that he was shot by three members of the Oriental Lazyboy street gang when he resisted a robbery attempt to get loot for purchase of rock cocaine. He left no will, and both his niece Sophia and relatives in Cambodia laid claim to the estate.

Dr. Ngor's best known role was that of Dith Pran, the Cambodian assistant to New York Times correspondent Sydney Schanberg in the 'Killing Fields'. A gynecologist and surgeon, Ngor was ordered out of Phnom Penh along with the rest of the city's 2 million inhabitants after the Khmer Rouge takeover in 1975. He was sent to the country's Northwest Zone, where middle-class Cambodians were turned overnight into peasant farmers in a classless society. Fearing for his life if his level of education were revealed, Ngor constantly attempted to disguise his medical knowledge, hiding his glasses and ignoring atrocities in the Khmer camp. When a Vietnamese invasion ousted the Khmer Rouge in 1979, Ngor escaped to Thailand and in 1980 settled in the U.S. While working in various television and movie roles, Ngor continued to work for the benefit of Cambodian refugees, including co-founding two major refugee aid societies.