William H. Regnery II, the heir to a family textile fortune who was known for his quiet but influential support of extreme right-wing causes in the United States, died July 2 at his home in Boca Grande, Fla. He was 80.

A person at the Lemon Bay Funeral Home and Cremation Services in Englewood, Fla., on Saturday confirmed that the funeral home handled arrangements for Mr. Regnery. A cousin told the New York Times that he had cancer.