Fred Hiatt, the longtime editorial page editor of The Washington Post, who used his position atop one of the nation’s most visible and influential opinion platforms to support justice and human rights, died Dec. 6 at a hospital in Manhattan. He was 66.

Mr. Hiatt, a three-time finalist for the Pulitzer Prize in editorial writing, led The Post’s opinion section for more than two decades. In that time, he expanded the staff from about a dozen people to more than 80, broadening its reach and its ranks to include not only seasoned journalists, but also younger, up-and-coming writers, videographers, bloggers and designers.

Mr. Hiatt was best known in recent years, perhaps, for leading the newspaper’s outraged response to the 2018 abduction and murder of one of its Saudi contributors, Jamal Khashoggi, and also his view that Donald J. Trump was unfit to be president of the United States. In 2016, before the general election was underway and long before Mr. Trump was twice impeached, Mr. Hiatt wrote that Mr. Trump’s “contempt for constitutional norms might reveal the nation’s two-century-old experiment in checks and balances to be more fragile than we knew.” He was a Pulitzer finalist for his editorials about Mr. Trump.