This most interesting and unusual surname is of Old Spanish origin, and derives from a medieval personal name of uncertain origin, but which is probably a metathesized form of the Latin "Orosius", from the Greek "Orosios", a derivative of "oros", mountain. Hence, the name was probably given in some instances as a nickname to a rather large, round man. The personal name was borne by a 4th Century Iberian theologian and historian, who was famous in Spain throughout the Middle Ages. The surname can also be of specifically Basque origins however, and was given to a hunter of wolves. Early recordings include the christening of Gaspar, son of Miguel and Ysabel Osorio, on February 3rd 1579, at Nuestra Senora La Antiqua Salobre, Albacete; the christening of Ynes, daughter of Pedro and Theresa Osorio, on October 17th 1592; and the marriage of Abraham Osorio to Rebecca Da Costa on June 22nd 1726, at St. Margaret's, Lothbury, London. A Coat of Arms granted to families of the name, of Galice, Leon and Valence, depicts two red passant wolves, one above the other, on a gold shield. The first recorded spelling of the family name is shown to be that of Ana Garcia de Osorio, which was dated 1522, marriage to Herando Pedroso de Astorga, at Toro, Orense, Spain, during the reign of King Charles 1 of Spain, 1516 - 1556. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.