Dale Jennings, a dedicated gay rights activist and author of “The Cowboys,” a novel that eventually found its way to the screen, died May 11 at Specialty Hospital in La Mirada. He was 82.

Jennings, a founder of the gay rights movement, made his mark in Hollywood with “The Cowboys.” After it was published Jennings sold the rights to WB, which produced it as a film starring John Wayne in 1972.

A strong-willed and tough-minded activist, Jennings co-founded the Mattachine Society — regarded as the first modern gay U.S. organization — in 1950. Then, in 1952, Jennings co-founded One, the first proudly gay public magazine dedicated to taking a stand for homosexuals. The magazine was confiscated by the L.A. postmaster in 1954 on the basis of obscenity but was re-released onto newsstands after a 1958 U.S. Supreme Court ruling that a magazine calling for equality of homosexuals is not in itself obscene.

This decision was the basis for the future growth of the gay and lesbian press.

After being honorably discharged from the Army, Jennings spent the next two years of his life attending theater school at USC.

Over the years Jennings contributed various articles and book reviews to the magazines One and Tangents. He also wrote such published books as “The Ronin” and “The Sinking of the Sarah Diamond.”

Jennings, who was born in Amarillo, Texas, leaves behind some 125 unpublished movie scripts and books.

He is survived by a nephew.

A memorial service will be held at 2 p.m. on June 18, at the One Institute & Archives at USC. The public is invited. Funds in Jennings’ memory can be donated to One Institute & Archives, 909 West Adams Blvd., Los Angeles, 90007, for the preservation of his work and collection.