Guillermo Klein (1969- ) is an Argentine pianist and composer. He moved from Argentina to Boston in 1990 to study jazz composition and arranging at Berklee College of Music. In 1993 he moved to New York where he formed a 17-piece big band. The band played Sunday nights at the underground club Smalls throughout 1995. Several years later, the new Jazz Standard club gave the Guillermo Klein Big Band a regular Monday night gig for several months. Klein began performing and recording with a ten-piece ensemble called Los Guachos, which featured the likes of Bill McHenry, Chris Cheek, Ben Monder, Jeff Ballard and others. The other half the band was composed primarily of South American-native musicians including Fernando Huergo, Diego Urcola, Juan Cruz de Urquiza, Claudi Acuna, and later Luciana Souza and Miguel Zenon. The band's debut on Candid Records was never released, but Sunnyside picked up Los Guachos Vol. 2 for release in 1999. Klein moved back to Argentina in September of 2000 and has since split much of his time between Argentina and Spain. He occasionally plays in the United States, appearing primarily at the Village Vanguard in New York City. He was commissioned by the MIT Wind Ensemble to write a piece, Solar Return Suite, his first work for wind ensemble, which was premiered on May 12, 2006.