Willi Apel (October 10, 1893 – March 14, 1988) was a German-American musicologist and noted author of a number of books devoted to music.Apel was born in Konitz, West Prussia, now Chojnice in Poland. He studied mathematics from 1912 to 1914, and then again after World War I from 1918 to 1922, in various universities in Weimar Germany. Throughout his studies, he had an interest in music and taught piano lessons. He then turned to music full-time, and essentially taught himself about musicology.