Callen Radcliffe Tjader Jr. ( JAY-dər; July 16, 1925 – May 5, 1982) was an American Latin Jazz musician, often described as the most successful non-Latino Latin musician. He explored other jazz idioms, especially small group modern jazz, even as he continued to perform music of Afro jazz, the Caribbean, México and Latin America.

Tjader played the vibraphone primarily, but was accomplished on the drums, bongos, congas, timpani, and the piano. He worked with many musicians from several cultures. He is often linked to the development of Latin rock and acid jazz. Although fusing Jazz with Latin music is often categorized as "Latin Jazz", Tjader's works swung freely between both styles. His Grammy award in 1980 for his album La Onda Va Bien capped off a career that spanned over forty years.