Big Sir was an American musical duo from Los Angeles, California. It was founded in 2000 by Juan Alderete and singer Lisa Papineau. Big Sir recorded a total of four albums between then and 2014. The duo began when Papineau's previous band, Pet, dissolved in the late 1990s. The duo released a self-titled album in 2000, but did not release any more projects until 2006 due to Alderete's involvement with the Mars Volta.