Roberto León Grela, born on June 28, 1913, in the San Telmo neighborhood of Buenos Aires, Argentina, was a distinguished tango guitarist and composer. His musical journey began in a family environment rich with musical influence, as his father and uncle formed the duo Los Hermanos Belpasso. Initially inclined towards the mandolin, Grela was persuaded by the guitarist Manuel Parada to switch to the guitar at the age of seven.

Grela's professional career commenced in 1930 when he began playing guitar on radio LR3, accompanying Roberto Maida. Over the years, he collaborated with numerous tango artists, including Charlo, Jorge Casal, Osvaldo Cordó, and Edmundo Rivero, among others. His partnership with the renowned bandoneonist Aníbal Troilo was particularly significant, creating a unique and profound synergy that left a lasting impact on tango music.

In addition to tango, Grela briefly explored Argentine folk music and even led a jazz group called Los American Fire. He was known for his distinctive use of a pick, which contributed to his unique sound, despite some criticism. His self-taught style and ability to play by ear allowed him to infuse the guitar with the expressive phrasing of the bandoneon tradition.

Throughout his career, Grela was involved in various musical projects, including forming the San Telmo Quartet with Leopoldo Federico and participating in the show "Tango" at the Teatro Colón in 1964. He also appeared in the 1964 film "Buenas noches, Buenos Aires," directed by Hugo del Carril.

Roberto Grela passed away on September 6, 1992, in Buenos Aires, leaving behind a legacy as one of the most revered tango guitarists, celebrated for his exquisite sensitivity and rare musical ability.