Marcelo Ostria Trigo (born February 23, 1935), is a Bolivian attorney, government official, diplomat, university professor, columnist and author.

During his appointment as Under Secretary of the Ministry of Foreign Affairs, he participated as part of the Bolivian Delegation in the Bolivia-Chile presidential meeting of Charaña in 1975.

He also served as the Foreign Policy Adviser (2005) to former ad interim President of Bolivia, Eduardo Rodríguez Veltzé.

He is also a writer and poet and has authored a poetry book called "Baladas mínimas" (Editorial El País, 2010).

He has been honored with the Grand Cross of the Order of the Condor of the Andes, the highest state award for exceptional merit, either civil or military, shown by Bolivians or foreign nationals.