Paul Kantner, a co-founder of pioneering psychedelic group Jefferson Airplane who continued as a core member of successor group Jefferson Starship, has died at age 74. The cause of his death, the San Francisco Chronicle reports, was multiple organ failure and septic shock.

Kantner started Jefferson Airplane in the mid-1960s with Marty Balin and other musicians including guitarist Jorma Kaukonen; the group released their debut album in 1966. After original vocalist Signe Anderson left to raise her newborn daughter, the group completed their classic lineup with the addition of vocalist Grace Slick.

In 1967, Surrealistic Pillow — featuring songs like "White Rabbit" and "Somebody to Love" — cemented the band's place in rock history. One of the definitive psychedelic rock albums, the album helped provide the soundtrack to the Summer of Love. As a songwriter, rhythm guitarist, and vocalist, Kantner was "the catalyst that brought the whole [sound] together," said lead guitarist Kaukonen.

Jefferson Airplane became the only band to play at all three of the best-known rock festivals of the '60s: Woodstock, Monterey Pop, and the infamous Altamont Speedway festival at which a fan died after being stabbed by one of the Hells Angels who had been hired as security.

The band's commercial fortunes declined after 1967 follow up After Bathing at Baxter's, and with the band's personal and professional tumult increasing, Balin left the band in 1971. Kantner and Slick had a romantic relationship, and their daughter China Wing Kantner was also born that year.

Jefferson Airplane played their last show under that name in 1972, and in 1974 Kantner and Slick joined with David Freiberg to form a band they called "Jefferson Starship." Balin subsequently joined the new band, which despite ups and downs ultimately achieved more lasting commercial success than Jefferson Airplane had; their hits included "Miracles" (1975) and "Count on Me" (1978).

By 1984's Nuclear Furniture, turnover left Kantner as the only founding Jefferson Airplane member who remained in Jefferson Starship. When Kantner left, singer Mickey Thomas joined with Slick and others to form yet another new group: Starship, which achieved blockbuster chart success with their 1985 album Knee Deep in the Hoopla, featuring number one hits "We Built This City" and "Sara."

Kantner continued to play music for the remainder of his life, including occasional reunions with his former bandmates. Jefferson Airplane were inducted into the Rock and Roll Hall of Fame in 1996, and this spring they'll receive a Lifetime Achievement Grammy Award.