| Oscar Castelo | |
| Office: | Secretary of National Defense |
| President: | Elpidio Quirino |
| Predecessor: | Ramon Magsaysay |
| Successor: | Ramon Magsaysay |
| Term Start: | March 1, 1953 |
| Term End: | December 30, 1953 |
| Office2: | Secretary of Justice |
| President2: | Elpidio Quirino |
| Predecessor2: | Jose P. Bengzon |
| Successor2: | Roberto Gianzon |
| Term Start2: | January 1, 1952 |
| Term End2: | August 16, 1953 |
| Birth Name: | Oscar Tombo Castelo |
| Birth Date: | 20 May 1903 |
| Birth Place: | Cabanatuan, Nueva Ecija, Philippine Islands |
| Death Place: | Los Angeles, California, U.S. |
| Occupation: | Lawyer |
Oscar Tombo Castelo (May 20, 1903 – June 20, 1982) was a Filipino judge of the Manila Court and Secretary of National Defense of the Philippines.Born in Cabanatuan, Nueva Ecija, Castelo enrolled at the San Juan de Letran and later at Escuela de Derecho. He was admitted to the Philippine Bar in 1927 and was equally fluent in English and Spanish. He later moved to United States, where he died on June 20, 1982, aged 79.[1]