Osera de Ebro is a municipality in the province of Zaragoza, within the autonomous community of Aragon, Spain. It lies on the left bank of the Ebro River at an elevation of 174 m above sea level and occupies a total area of approximately 24–24.56 km². According to the municipal register (INE) for 2024‑2025, the population is around 428–442 inhabitants, giving a density of about 17–18 inhabitants per km².
The municipality forms part of the Comarca Central and belongs to the Mancomunidad de la Ribera Izquierda del Ebro. A significant portion of its territory is included in the Reserva Natural Dirigida de los Sotos y Galachos del Ebro, a protected natural area along the river. Major transport routes crossing Osera de Ebro include the AP‑2 highway and the N‑2 national road.
Historically, the first documented reference to the settlement dates to 1138. During the Middle Ages and early modern period the land was held by various feudal lords, including the Lords of Alfajarín (1138–1382) and later the Barony of Quinto. From 1626 it was part of a marquisate. The name “Osera” is thought to derive either from local bears that once came down from the mountains to drink at the river or from a place where many bones were found.
Key landmarks include the bell tower of the Church of Santa Engracia (originally built in 1575 and restored in 1985) and the remains of a medieval castle. The current mayor (as of 2019) is Enrique Gómez, representing the Cs (Ciudadanos) party.
Osera de Ebro maintains an official website at www.osera.deebro.es.
