Budd Hopkins, a distinguished Abstract Expressionist artist who — after what he described as a chance sighting of something flat, silver, airborne and unfathomable — became the father of the alien-abduction movement, died on Aug. 21 at his home in Manhattan. He was 80.

The cause was complications of cancer, his daughter, Grace Hopkins-Lisle, said.

A painter and sculptor, Mr. Hopkins was part of the circle of New York artists that in the 1950s and ’60s included Mark Rothko, Robert Motherwell and Franz Kline.

His work — which by the late ’60s included Mondrian-like paintings of huge geometric forms anointed with flat planes of color — is in the collections of the Metropolitan Museum of Art and the Museum of Modern Art in New York, the Corcoran Gallery of Art in Washington and the British Museum, among others.

In later years Mr. Hopkins turned to large, quasi-architectural sculptures that seemed to spring from primordial myths. In 1985, reviewing one such piece, “Temple of Apollo With Guardian XXXXV” — it was part house of worship, part archaeological ruin, part sacrificial altar — Michael Brenson wrote in The New York Times:

“If the work is about sacrifice and violence, it is also about ecstasy and illumination. In the course of trying to re-establish the broadest meaning of the abstract geometry that has fascinated so many 20th-century artists, Hopkins makes us consider that ritual, worship, cruelty and superstition have always been inseparable.”