| Horacio Tomás Liendo | |
| Office: | President of Argentina (Acting) |
| Term Start: | 21 November 1981 |
| Term End: | 11 December 1981 |
| Predecessor: | Roberto Eduardo Viola |
| Successor: | Carlos Lacoste (interim) |
| Office1: | Minister of the Interior |
| Term Start1: | 29 March 1981 |
| Term End1: | 12 December 1981 |
| Predecessor1: | Albano Harguindeguy |
| Successor1: | Alfredo Oscar Saint Jean |
| Office2: | Chief of the Joint Chiefs of Staff of the Armed Forces of the Argentine Republic |
| Term Start2: | 2 January 1980 |
| Term End2: | 29 March 1981 |
| Predecessor2: | José María Romero |
| Successor2: | Llamil Reston |
| Office3: | Minister of Labor |
| Term Start3: | 29 March 1976 |
| Term End3: | 8 February 1979 |
| Predecessor3: | Miguel Unamuno |
| Successor3: | Llamil Reston |
| Birth Date: | day=17 month=12 year=1924 |
| Birth Place: | Córdoba Province, Argentina |
| Death Place: | Buenos Aires, Argentina |
| Branch: | Argentine Army |
| Allegiance: |  Argentina |
| Rank: | (Pre-1991 epaulette) Division General |
| Serviceyears: | 1947-1981 |
Horacio Tomás Liendo (17 December 1924 – 27 August 2007) was an Argentinian military officer, who served in various positions during the National Reorganization Process such as Minister of Labour between 1976 and 1979,[1] and also Minister of Interior in 1981. Moreover, he was in charge of the presidency of Argentina during 21 days in 1981.[2]
He was born in Cordoba and was formed as Army officer at the Colegio Militar de la Nación. When President Roberto Eduardo Viola was suffering a heart ailment in 1981, he became acting president. He died in Buenos Aires at age of 82.[3]