Joseph Yasser (April 16, 1893 – September 6, 1981) was a Russian–American organist, music theorist, author, and musicologist. An influential figure who established a handful of musical institutions, Yasser is noted for his 1932 publication, A Theory of Evolving Tonality. He was active until his death at age 88 in 1981. Yasser was married but had no children.