Groundbreaking Los Angeles-based disc jockey Jim Ladd, whom Tom Petty & The Heartbreakers immortalized in their 2002 song “The Last DJ,” died suddenly Sunday of a heart attack. He was 75.

A Los Angeles fixture, Ladd worked up and down the Los Angeles radio dial, including stints at KNAC, KMET and KLOS. He was considered the last freeform DJ in the country, allowed to pick his own song selections.

After leaving KLOS in 2011, he was quickly picked up by SiriusXM’s Deep Tracks channel, where he appeared until his death. Over the decades, he was well known for his interviews with such artists as John Lennon, Pink Floyd,  Stevie Nicks and Led Zeppelin.

The Doors drummer John Densmore paid tribute to Ladd on social media, posting on X, “’The Last DJ’ has crossed the tracks. There wasn’t a more soulful spinner of music. The songs he played were running through his blood, he cared so much for rock n’ roll. Irreplaceable… a very sad day, which can only be handled by carrying his spirit forward.”

Densmore’s Doors bandmate Robby Krieger also posted, “Rest in peace, Jim Ladd. He was the best friend in radio The Doors ever had. Even when people forgot about us in the late ‘70s, he kept playing our music.“

Ladd started his career  at Long Beach, Calif.’s KNAC in 1969 as FM radio was burgeoning and quickly established himself as one of Southern California’s leading rock voices. In an undated interview with Michael Simone, he said of his mentors and being at the forefront of FM radio, “We were inventing this thing as we were going along, so what I would say in radio [for role models], it is pretty much everybody that I’ve worked with that I’ve learned from or borrowed from. … As far as role models in my life, Martin Luther King would be one, and certainly when I was growing up, John Lennon and Jim Morrison were two others who had a great influence on me, as well as [Roger] Waters.”

Waters and Ladd had a long friendship, with Ladd playing a rebel DJ on Waters’ 1987 Radio K.A.O.S. album and touring with Waters on the Radio K.A.O.S. On the Road outing.

From KNAC, Ladd moved to KLOS in 1971 and then had stops at Los Angeles stations KMET, KMPC and KLSX before returning to KLOS in 1997, where he stayed for 14 years. As Billboard reported in 2011, when he was let go from KLOS after Cumulus bought the station, he signed off with Pink Floyd’s “Shine On Your Crazy Diamond.”

Ladd inspired “The Last DJ” song, which Petty told journalist Jim DeRogatis was “about a DJ who becomes so frustrated with his inability to play what he wants that he moves to Mexico and gets his freedom back.”

Flowers will be placed on Ladd’s star on the  Hollywood Walk of Fame at 11 a.m. on Tuesday. He received his star in 2005. “His legendary voice and unparalleled contribution to the world of radio have left an indelible mark on the industry,” Ana Martinez, producer of the Hollywood Walk of Fame star ceremonies, stated in a statement. “Jim’s passion for music and his unique ability to connect with his listeners will always be remembered fondly.”

SiriusXM is airing tributes to Ladd, who is survived by wife Helene, on Deep Tracks as well as other classic rock channels.