NEW YORK — Outspoken radio personality Bill "Rosko" Mercer died Tuesday night, after a nine-year battle with cancer, according to a report by the Daily News.

The famed DJ, who was in his 60s, pioneered what he called "mind excursion" radio in the late 1960s, presenting music and monologue in a free-form manner. Mercer gained a cult following that reveled in his late-night poetic rants, music and social commentary.

"If you were a fan of late-night radio in the late '70s and early '80s, he was the man," Earl Douglas, a former WNEW-FM producer, said. "It was like a secret society of radio, and anyone could join."

After working in Los Angeles, Mercer joined New York's WOR-FM in 1966, where he and DJs Murray the K, Scott Muni and Johnny Michaels pushed the envelope of experimental radio. WOR-FM was the first FM station to broadcast rock 'n' roll.

"I considered Rosko a friend," Muni, now at Q104-FM in New York, said. "His contribution to New York radio was huge."

"Guys like Paul Simon and John Sebastian would come by and hang out in the studio all the time while we were on the air," former WOR-FM engineer Artie Altro said. "All these guys would come by with records straight from the recording studio because they knew we would play 'em.

"After a year or so [Program Director Bill] Drake was hired, and his format was very restrictive in what … they could say or play on the air," Altro said. "Rosko and those guys had their own ideas, which were very popular with the audience but not with Drake."

In October 1967, Mercer shocked the station's management by announcing his resignation during a broadcast, citing fundamental differences with the station's format.

"When are we going to learn that controlling something does not take it out of the minds of people?" Mercer told his radio audience the night he quit. "Usually, when a disc jockey leaves a station, his reasons for leaving are smoothed over, perhaps by time. I didn't want that to happen. I wanted you to know now."

That same year, Mercer moved to WNEW-FM, where he wrote poetry and appeared on music discussion panels that spanned the rest of his career. A 1969 promotional radio spot recorded by Mercer appears on an untitled French EP included in a Velvet Underground box set released in 1990.

Mercer, who is featured in a radio exhibit at the Rock and Roll Hall of Fame museum, lived in France in the mid-'70s before returning to New York at the end of the decade to broadcast on WBLS-FM and WKTU-FM. In 1985, Mercer quit WKTU-FM while on the air, because of a reported dispute with the station's hierarchy.

Q104-FM on-air personality Maria Milito met Mercer while she was at WKTU, in 1984, and the two became close friends.

"[Rosko's death] is a great loss to all of us," Milito said. "He was his own person — poetic and philosophical, all rolled into one.

"Rosko hated pretentiousness," she added. "He kept it real before 'keepin' it real' became a cliché. He will truly be missed."

In the latter part of his career, Mercer continued to write poetry and returned to broadcasting, albeit infrequently, on New York's WBAI-FM. He was diagnosed with cancer in 1991.

"He set the ultimate standard for professionalism," veteran WBAI DJ

Delphine Blue said. "The studio was a sacred place to him."