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 later the dean of the White House briefing room, died Saturday at 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 that 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.”...