Abhayavongsa (Thai: อภัยวงศ์; rtgs: Aphaiwong) is a Thai noble surname used by a Khmer family that was prominent in parts of Cambodia formerly ruled by Siam.
The Abhayavongsa family, a branch of the Cambodian royal family, governed Phra Tabong Province, Thailand (modern Battambang Province, Cambodia) for six generations from the late 18th century, when Siam annexed the Khmer territories, until 1907, when the area was ceded to French Indochina effectively reuniting it with Cambodia. The title bestowed to the governor of Phra Tabong and used by each successive governor was Chao Phraya Abhaibhubejr (Thai: เจ้าพระยาอภัยภูเบศร์).
In later years, the Abhayavongsa family played important roles in the anti-French struggle for Cambodian independence and one descendant became Prime Minister of Thailand. During World War II, Thailand regained control of the western Khmer provinces through Japanese mediation. Khuang Abhayavongsa was elected Prime Minister of Thailand, an office which he held three separate times between August 1944 and April 1948. Through family business ties, Khuang maintained close ties with the western Cambodian provinces during his time in office and fought, to no avail, to keep them under Thai rule in the wake of the Japanese loss and resurgence of the French in Indochina. His brother Chaowalit Aphaiwong worked until 1946 in a "Special Commission" in Battambang and was considered the "Nominal Head of the Khmer Issarak movement" fighting French rule of Cambodia. The official head of the Khmer Issarak movement was Phiset Phanit (Pokhun), Khuang's brother-in-law. A French report of the era went so far as to claim "[t]he Khmer Issarak movement is both a political and commercial affair of the Aphaiwong family".
Members of the Abhayavongsa family include: