John Francis Anthony Pastorius III (December 1, 1951 – September 21, 1987), known as Jaco Pastorius, was an influential American jazz musician, composer, big band leader and electric bass player. He is best known for his work with Weather Report from 1976 to 1981, as well as work with artists including Joni Mitchell and his own solo projects.

His playing was known for its highly technical, Latin-influenced 16th-note funk, lyrical soloing on fretless bass and innovative use of harmonics. He was inducted into the Down Beat Jazz Hall of Fame in 1988, one of only seven bassists so honored (and the only electric bass guitarist).

In his early career Pastorius had avoided alcohol and drugs, but with Weather Report he increasingly used alcohol and other drugs, the abuse of which exacerbated his mental issues, leading to increasingly erratic and sometimes anti-social behavior.



Pastorius was diagnosed with bipolar disorder in late 1982 following the Word of Mouth tour of Japan, in which his erratic behavior became an increasing source of concern for his band members. Drummer Peter Erskine's father, Dr. Fred Erskine, suggested that Pastorius was showing signs of the condition and, on his return from the tour, his wife, Ingrid, had Pastorius committed to Holy Cross hospital under the Florida Mental Health Act, where he received the diagnosis and was prescribed lithium to stabilize his moods.

He had shown numerous features of the condition long before his initial diagnosis, though they were too mild to diagnose at the time as mental illness – being regarded instead as eccentricities or character flaws. Hypomania, the cyclical peaks in mood that distinguish bipolar disorder from unipolar depression, have been associated with enhanced creativity, with his friends and family recognizing retrospectively that these peaks played an essential role in his urge to create music.