Ivan Karp, a cigar-chomping, fast-talking New York gallery owner who helped find, popularize and market the Pop artists of the 1960s, including Andy Warhol, Roy Lichtenstein and Robert Rauschenberg, died on Thursday at his home in Charlotteville, N.Y. He was 86.

His wife, Marilynn, said he died of natural causes.

Mr. Karp always found the time to look at the slides of dozens of aspiring artists who each week asked him for the chance of a lifetime. He responded with precious gallery space, encouragement, a referral to a more appropriate dealer or rejection.

As Pop blossomed, Mr. Karp took to the road and made hundreds of speeches promoting the new art form — not to mention appearances on television shows like “The Tonight Show.”

In 1969, Mr. Karp was one of the first gallery owners to follow artists to SoHo, an industrial area that would quickly become as much an art gallery district as the Upper East Side. His O K Harris Works of Art — first at 485 West Broadway, then at its present address, 383 West Broadway — would become the first gallery on one of SoHo’s principal boulevards. He, like several other pioneers to venture south of Houston Street, liked to think of himself as SoHo’s unofficial mayor.