Juan Mostazo Morales, born on July 18, 1903, in Seville, Spain, was a prominent Spanish composer known for his contributions to the genre of copla. He was active during the early 20th century, creating many beloved songs that have become staples in Spanish music. Among his most famous compositions are "La Bien Pagá," "Mi Jaca," "La Falsa Monea," "Échale guindas al pavo," "Pregón de la Gitana," "El Día que Nací Yo," and "Antonio Vargas Heredia."

Mostazo's career was marked by significant collaborations, notably with lyricist Ramón Perelló, with whom he crafted many popular songs of the era. Their first successful collaboration was "Mi Jaca," performed by Estrellita Castro in 1934. He also worked with other composers like José Gardey Cuevas and Luis Rivas Gómez under the pseudonym "Garrimos."

In addition to his songwriting, Mostazo composed music for films, including "Carmen la de Triana" (1938) and "Morena Clara" (1936), both of which featured songs performed by notable artists such as Imperio Argentina and Estrellita Castro. His music was integral to several films directed by Florián Rey.

Juan Mostazo passed away on November 17, 1938, in his hometown of Seville due to a sudden attack of uremia. Despite his early death at the age of 35, his work left a lasting impact on Spanish music, and his songs continue to be celebrated and performed by artists across generations.