Oas, officially the Municipality of Oas (Central Bikol: Banwaan kan Oas; Filipino: Bayan ng Oas), is a municipality in the province of Albay, Philippines. According to the 2020 census, it has a population of 66,084 people.

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There are two stories that purport to tell the origin of the name of Oas:

a) There is a dam across the narrowest portion of a local river. This dam solely irrigates the vast fields of the place including those of the nearby town of Libon and results in a good harvest. People are wary of any cracks or leaks on the dam walls during months of heavy rains. A crier would shout nawaswas, giving the call to the people (in times of this kind of emergency) for immediate action in groups. From then on, the natives coined this name for the place and later shortened it to present form.

b) Early Spanish colonizers reaching this particular section of the Bicol Peninsula asked the name of the place from the about 600 natives living there, "Como se llama este sitio?" The natives mistakenly thought the question to be "Onan kading lugar kadi, maiwas?" ("What place is this, it's very big?") in their native language. In response, the natives answered, "Si, señores. Labi nikading iwas. Labi nikading iwas." ("Yes, sirs, this is grand and spacious".) From then on the early Spanish colonizers adopted in their official census the existence of "a rich fertile valley with verdant fields of grain" which is the little town of Oas in Bicol.

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Oas was founded during the early Spanish colonization of the Bicol Peninsula. In 1605, Father Baltazar de los Reyes converted 12 leading natives of the area to Christianity in one day, forming the foundation of the community now known as Oas.

The town was one of the localities particularly harmed by the Dictatorship of Ferdinand Marcos; in the waning days of the dictatorship, Oas was hit by a series of political killings targeting those who dared to speak out against the abuses of the Military and against Ferdinand Marcos.

The most prominent of the victims was Clemente Ragragio, the municipal sanitation inspector of Ligao who was later also assigned to Oas. Known for his effectiveness, he had been awarded the 1983 Best Sanitary Inspector for Albay. However, this led the dictatorship's local administrators suspecting him of being a rebel sympathizer, because his close relationship with locals in far-flung barangays allowed him to move around fearlessly, and because he expressed disagreements with the dictatorship's governance. A killer shot him three times in front of his house in the early evening of August 21, 1985, and the government did not investigate his murder. He was later honored by having his name inscribed on the wall of remembrance at the Philippines' Bantayog ng mga Bayani (lit. Monument of Heroes), which honors the martyrs and heroes who fought to restore democracy in the wake of the Marcos dictatorship.

Oas has been in the news several times in recent years due to the achievements of its outstanding citizens, notably chess prodigy Bince Rafael Operiano who topped the under-10 age category at the 6th Eastern Asia Youth Chess Championship in Bangkok in 2022, and Miss Universe 2018 Catriona Gray whose maternal lineage has its roots in Oas.

Oas is located at 13°15′32″N 123°29′43″E / 13.2589°N 123.4953°E / 13.2589; 123.4953.

According to the Philippine Statistics Authority, the municipality has a land area of 263.61 square kilometres (101.78 sq mi)  constituting 10.23% of the 2,575.77-square-kilometre- (994.51 sq mi) total area of Albay.

Oas is 32 kilometres (20 mi) from Legazpi City and 495 kilometres (308 mi) from Manila.

Oas is politically subdivided into 53 barangays. Each barangay consists of puroks and some have sitios.

PSGC	Barangay	Population			±% p.a.
		2020		2010
050512001	Badbad	0.9%	622	583	▴	0.65%
050512002	Badian	4.1%	2,681	2,348	▴	1.33%
050512003	Bagsa	1.3%	862	764	▴	1.21%
050512004	Bagumbayan	1.3%	879	1,018	▾	−1.46%
050512005	Balogo	7.9%	5,236	3,897	▴	3.00%
050512008	Banao	0.7%	470	562	▾	−1.77%
050512009	Bangiawon	1.4%	910	785	▴	1.49%
050512011	Bogtong	0.6%	367	351	▴	0.45%
050512010	Bongoran	2.7%	1,816	1,741	▴	0.42%
050512012	Busac	3.1%	2,079	1,939	▴	0.70%
050512013	Cadawag	0.7%	485	427	▴	1.28%
050512014	Cagmanaba	5.0%	3,305	3,039	▴	0.84%
050512015	Calaguimit	1.3%	867	865	▴	0.02%
050512016	Calpi	2.0%	1,335	1,224	▴	0.87%
050512017	Calzada	1.4%	911	1,029	▾	−1.21%
050512018	Camagong	1.8%	1,167	1,146	▴	0.18%
050512019	Casinagan	0.9%	617	530	▴	1.53%
050512020	Centro Poblacion	0.3%	225	277	▾	−2.06%
050512021	Coliat	1.1%	723	717	▴	0.08%
050512022	Del Rosario	1.1%	733	624	▴	1.62%
050512023	Gumabao	1.2%	793	865	▾	−0.87%
050512024	Ilaor Norte	2.3%	1,495	1,525	▾	−0.20%
050512025	Ilaor Sur	3.3%	2,202	2,275	▾	−0.33%
050512026	Iraya Norte	3.0%	1,982	1,909	▴	0.38%
050512027	Iraya Sur	1.2%	779	711	▴	0.92%
050512028	Manga	3.5%	2,322	2,146	▴	0.79%
050512029	Maporong	1.8%	1,184	1,107	▴	0.67%
050512030	Maramba	5.0%	3,301	3,114	▴	0.58%
050512032	Matambo	0.7%	489	435	▴	1.18%
050512033	Mayag	0.7%	452	507	▾	−1.14%
050512034	Mayao	2.4%	1,618	1,514	▴	0.67%
050512031	Moroponros	0.5%	357	283	▴	2.35%
050512035	Nagas	2.5%	1,631	1,665	▾	−0.21%
050512037	Obaliw-Rinas	2.3%	1,504	1,401	▴	0.71%
050512038	Pistola	1.7%	1,135	1,101	▴	0.30%
050512039	Ramay	1.1%	734	724	▴	0.14%
050512040	Rizal	1.3%	864	892	▾	−0.32%
050512041	Saban	2.9%	1,908	1,875	▴	0.17%
050512042	San Agustin	1.9%	1,285	1,240	▴	0.36%
050512043	San Antonio	1.4%	939	938	▴	0.01%
050512044	San Isidro	2.3%	1,529	1,400	▴	0.89%
050512045	San Jose	1.1%	744	759	▾	−0.20%
050512046	San Juan	2.3%	1,503	1,390	▴	0.78%
050512047	San Miguel	1.2%	772	792	▾	−0.26%
050512036	San Pascual (Nale)	1.3%	841	743	▴	1.25%
050512049	San Ramon	2.6%	1,710	1,657	▴	0.32%
050512050	San Vicente (Suca)	1.4%	938	1,046	▾	−1.08%
050512056	Tablon	1.4%	940	903	▴	0.40%
050512051	Talisay	1.2%	777	693	▴	1.15%
050512052	Talongog	1.8%	1,198	1,144	▴	0.46%
050512053	Tapel	2.7%	1,810	1,371	▴	2.82%
050512054	Tobgon	2.5%	1,649	1,517	▴	0.84%
050512055	Tobog	2.0%	1,313	1,277	▴	0.28%
	Total		66,084	64,785	▴	0.20%

Population census of Oas

Year	Pop.	±% p.a.
1903	11,393	—
1918	16,488	+2.49%
1939	23,131	+1.63%
1948	27,824	+2.07%
1960	36,095	+2.19%
1970	47,952	+2.88%
1975	50,293	+0.96%
1980	52,269	+0.77%
1990	53,061	+0.15%
1995	56,536	+1.20%
2000	62,063	+2.02%
2007	63,888	+0.40%
2010	64,785	+0.51%
2015	67,960	+0.92%
2020	66,084	−0.55%
Source: Philippine Statistics Authority

In the 2020 census, Oas had a population of 66,084. The population density was 250 inhabitants per square kilometre (650/sq mi).

Poverty incidence of Oas

10 20 30 40 50 2006 48.40 2009 42.93 2012 36.30 2015 31.79 2018 34.21 2021 31.38 Source: Philippine Statistics Authority

2022–2025 Oas Municipal Officials

Position	Name	Party
Mayor	Domingo R. Escoto, Jr. ‹›		PDP
Vice Mayor	Hector R. Loyola +		PDP
Councilors	Atty. Sharon R. Escoto +		PDP
	Arvin Gregg R. Ricarte +		Independent
	Leopoldo R. Zaragoza ‹›		PDP
	Jesus “Boy” R. Reario, II ‹›		Aksyon
	Noel D. Brijuega +		PDP
	Henry R. Raposon ‹›		Aksyon
	Gader B. Rellama ‹›		PDP
	Robert N. Arevalo +		PDP
Ex Officio Municipal Council Members
ABC President	Joseph Rentosa (San Isidro)		Nonpartisan
SK Federation President	Kyle Escalada (Rizal)		Nonpartisan

• David Nepomuceno - 1924 Olympian, first Filipino to compete in the Olympics
• Catriona Gray - Miss Universe 2018

• Philippine Standard Geographic Code
• Municipality of Oas