Jack Casady (born John William Casady, April 13, 1944), is an American musician considered one of the foremost bass guitarists of the rock music era. First playing in Washington D.C. area rhythm and blues bands, he became one of the founding members of Jefferson Airplane when Jorma Kaukonen invited him to join in the summer of 1965. Jefferson Airplane became the first successful exponent of the San Francisco sound, characterised as loud, raw, unpolished powerful rock and roll with plenty of feeling. Their singles, which had a more polished style, successfully charted in 1967 and 1968. They are one of the best remembered bands of the "psychedelic sixties." Casady also occasionally played with the other key San Francisco band, the Grateful Dead.