Juan Álvarez was born in Murcia in 1960. In 1978, after finishing his secondary studies, he temporarily moved to Madrid to work on animated cartoons. His first professional comic appeared in Senda del Comic in 1980. In 1982 he drew the educational 'Estatuto de Autonomía de la Región de Murcia'. In 1984 he won first prize in an amateur artists contest of magazine 1984. Then, he teamed up with artist Jorge Gómez, who coloured Álvarez's drawings in oil, which gave them an unforeseen look, emphasizing their volumes. However, the few short stories they published in the short-lived TBO of publisher Bruguera, Zona 84 and Tótem (second run) weren't enough to earn their living. By the late 1980s, Jorge Gómez was working as a fireman and Juan Álvarez was mainly working on animated cartoons again.
They rejoined to produce 'Los Mendrugos' for humorous weekly El Jueves in 1990. This series originated from 'MM el loco del claustro', a monthly comic strip that Álvarez had started in an university magazine in the mid-1980s. Subsequently, they created 'Capitana Diana' and 'Lucía, gabinete de sexología' for the publisher of El Jueves. The team collaborated on projects and activities related to comics in their native Murcia, such as the magazine El Tío Saín. During his career, Juan Álvarez also worked on illustration and advertising. Álvarez often did comic strips for press.