WASHINGTON — Helen Thomas, whose keen curiosity, unquenchable drive and celebrated constancy made her a trailblazing White House correspondent in a press corps dominated by men and who was later regarded as the dean of the White House briefing room, died on Saturday at her home in Washington. She was 92.

Her death was announced by the Gridiron Club, one of Washington’s leading news societies. Ms. Thomas was a past president of the organization.

Ms. Thomas covered every president from John F. Kennedy to Barack Obama for United Press International and, later, Hearst Newspapers. To her colleagues, she was the unofficial but undisputed head of the press corps, her status ratified by her signature line at the end of every White House news conference: “Thank you, Mr. President.”

Her blunt questions and sharp tone made her a familiar personality not only in the parochial world inside the Washington Beltway but also to television audiences across the country.