Rubén Armando Costas Aguilera (born 6 October 1955) is a Bolivian politician and the prefect and then governor of Santa Cruz Department in Bolivia from 2006 to 2021, and also the leader of the Democrat Social Movement (MDS).

[7]Costas ran as a member of the Truth and Social Democracy (VERDES) party, of which he was the leader, winning 54% of the popular vote and returning to the leadership of Santa Cruz on 30 May 2010.

On 12 April 2011, Costas was shot in the left temporal bone in the Blacutt Square of Santa Cruz de la Sierra after attempted to prevent the assault of a woman by two assailants on motorcycles.

Ahead of the 2014 general elections, Costas merged his VERDES party with Renewing Freedom and Democracy (LIDER), and Popular Consensus (CP), forming the Democrat Social Movement (MDS).

[13] The MDS did not present its own gubernatorial candidate to succeed Costas, instead choosing to endorse Creemos leader Luis Fernando Camacho, who ultimately won in the first round.