Ong is a Hokkien romanization of several Chinese surnames: 王 (Wáng in Hanyu Pinyin), 汪 (also Wāng), 黃 (traditional) or 黄 (simplified; Huáng); and 翁 (Weng). Ong is also a Laotian surname. Ong or Onge is also a surname of English origin, with earliest known records found in Western Suffolk taxation records from c. 1280 AD.^[1] Ong (or Онгь in Russian language-based records) is also an Estonian surname, possibly derived from õng, meaning "fishing rod/hook".

Ong has also been used to romanize the Taishanese pronunciation of 鄧 (more commonly romanized as Deng or Teng), as in the case of Betty Ong.

Under the Pe̍h-ōe-jī romanization system, 王 but not the other names includes a circumflex over its vowel: Ông. However, this is often omitted in practice.

In Singapore, Ong is the fifth-most-common surname among Singaporean residents. In the United States, Ong was the 6,682nd most common surname during the 1990 US census and the 4,343rd most common surname during the year 2000 US census.^[2]

• Angelia Ong (born 1990), Filipina model and beauty pageant titleholder
• Augustine Ong, Malaysian scientist and academic
• Ong Beng Hee (born 1980), Malaysian professional squash player
• Ong Beng Teong (born 1962), Malaysian badminton player and coach
• Betty Ong (1956–2001), American flight attendant, killed in the September 11 attacks
• Ong Boon Hua, birth name of Chin Peng, Malaysian politician and anti-fascist activist
• Ong Boon Pang (1882–1940), Bruneian businessman and Kapitan Cina
• Canny Ong (1974–2003), Malaysian murder and rape victim
• Cassandra Ong (born 2000), Filipino businesswoman
• Daniel Ong (born 1975), Singaporean businessman, radio DJ and television host
• Daryl Ong (born 1987), Filipino singer-songwriter
• Ong Ewe Hock (born 1972), Malaysian badminton player
• Glenn Ong (born 1970), Singaporean DJ
• Han Ong (born 1968), American playwright and novelist
• Ong Hock Thye (1908–1977), Malaysian judge
• Ong Hok Ham (1933–2007), Chinese Indonesian historian
• Ong Huay Dee (1935–2000), Singaporean taxi driver and murder victim
• Ong Iok-tek (1924–1985), Taiwanese scholar and politician
• John D. Ong (born 1933), American businessman
• Ong Ka Ting (born 1956), Malaysian politician
• Ong Kee Hui (1914–2000), Malaysian Chinese politician
• Ong Keng Sen (born 1963), Singaporean theatre director
• Ong Keng Yong (born 1954), Singaporean diplomat
• Ong Keo (?–1910), Laotian pro-independence rebel
• Ong Kham (?–1769), king of Luang Phrabang
• Ong Khan (?–1203), khan of the Keraites
• Ong Kim Kee (1931–1998), businessman and community leader
• Ong Kommandam (?–1910), Laotian pro-independence rebel
• Nai Phuan Ong (born 1948), American experimental physicist
• Olivia Ong (born 1985), Singaporean singer and actress
• Ong Pang Boon (born 1929), Singaporean retired politician
• Ong Poh Lim (1923—2003), Malaysian Singaporean badminton player
• Remy Ong (born 1978), Singaporean bowler
• Richard Ong (born 1965), Malaysian businessman and investor
• Ryan Ong Palao, Filipino-American drag performer and HIV awareness activist
• Samuel Ong (1945–2009), Filipino whistleblower
• Willie Ong, (born 1963) Filipino cardiologist, media personality and politician
• Ong Schan Tchow (1900–1945), Chinese patriot artist
• Ong Seok Kim (1884–1964), Malaysian educationist, social worker and philanthropist
• Ong Seong-wu (born 1995), South Korean singer and actor
• Ong Soh Khim, Singaporean academic and politician
• Ong Soo Hin, Malaysian Chinese businessman
• Ong Soon Hock (born 1985), Malaysian badminton player
• Ong Teck Chin (born 1949), Singaporean educator
• Ong Teng Cheong (1936–2002), Singaporean architect, union leader and politician
• Ong Teng Siew (born 1968), Malaysian chicken slaughterer and convicted killer
• Thomas Lembong, Indonesian politician
• Walter J. Ong (1912–2003), American Jesuit priest, professor and philosopher
• Ong Ye Kung (born 1969), Singaporean politician