The Rev. Jesse L. Douglas Sr., who as a longtime lieutenant to the Rev. Dr. Martin Luther King Jr. played a vital behind-the-scenes role in staging the historic civil rights marches from Selma to Montgomery in Alabama in 1965, has died in Charlotte, N.C. He was 90.

His daughter, Adrienne Douglas Vaulx, said he died in a nursing home on Feb. 17, 2021. His death was not widely reported at the time, and The New York Times, which had prepared an obituary in advance, did not learn of it until this week.

Mr. Douglas served the cause during the peak of the civil rights movement, from 1963 to 1966, as president of the Montgomery Improvement Association, a civic group founded in 1955 in response to the arrest of Rosa Parks for sitting in a whites-only section of a public bus. It had then organized a 13-month bus boycott under Dr. King’s leadership, leading to a Supreme Court ruling barring segregation on public buses.

For more than three decades, Mr. Douglas was on the national board of the Southern Christian Leadership Conference, the civil rights group that Dr. King helped form in 1957.

Mr. Douglas was respected for the calmness he displayed in handling the complicated logistics of the voting-rights marches that began in Selma.

The first, on March 7, a date now etched in history as “Bloody Sunday,” was brutally stopped in Selma along the Edmund Pettus Bridge by baton-wielding state troopers and local police. A second, smaller march was cut short by Dr. King two days later. A third try, beginning on March 21, swelled to some 25,000 participants escorted by the Alabama National Guard under federal control, as well as F.B.I. agents and federal marshals. It succeeded in reaching the State Capitol in Montgomery four days later.

Mr. Douglas was known for his resonant baritone singing voice — particularly his renditions, with lyrics adapted to the civil rights movement, of one of Dr. King’s favorite spirituals, “I Told Jesus It Would Be All Right if He Changed My Name.”

But Mr. Douglas, an albino with fair skin, blue eyes and blond hair, was perhaps best remembered for a widely circulated photograph by Steve Schapiro in which he is the lone pale figure among a group of Black Americans walking arm in arm in the third and final march from Selma.

In the photo, Mr. Douglas is flanked by Dr. King and John Lewis, who was then the chairman of the Student Nonviolent Coordinating Committee (SNCC). Mr. Lewis, who went on to have a distinguished career in Congress, had been badly beaten on “Bloody Sunday.”

In captions that ran with the photo in newspapers (Mr. Schapiro took both color and black-and-white versions), Mr. Douglas was invariably referred to as an “unidentified white man,” a label that was a vivid if not ironic reminder of how American society had long been anything but colorblind.

Jesse Lee Douglas was born on Aug. 19, 1930, in New Orleans. His father, Willie Lee Douglas, was a cook in the merchant marine. His mother, Isabelle, was a house maid.

The younger Mr. Douglas was educated at historically Black schools. He attended Dillard University, in New Orleans, before transferring to Lane College, in Jackson, Tenn., from which he graduated in 1959. In 1962, he received a doctor of ministry degree from the Interdenominational Theological Center in Atlanta.

It was in the library of the center that he met Dr. King in 1960. Dr. King was already a celebrated figure, and their encounter inspired Mr. Douglas to get involved in the civil rights movement. That year, he joined a protest to desegregate the cafeteria at the Georgia State Capitol.

As he explained in an interview for this obituary in 2018, because of his pale skin, he was designated to go into the cafeteria on his own. He sat down to eat without incident. But when other Black protesters showed up, they were turned down, and the cafeteria was closed.

He immediately left the cafeteria and placed a call with the Southern Christian Leadership Council’s legal affairs office, which filed a successful lawsuit in state courts, saying it was unconstitutional for state funds to be used to serve only one race. The ruling in the case, Douglas and Reynolds v. Vandenberg, made racial desegregation mandatory for all facilities at the Capitol building in Atlanta.

“I didn’t play a role,” he said. “I was just being myself. I was what you could call a reverse Oreo cookie — white on the outside, Black on the inside.”

After graduating from the theological center, he was assigned to the First Christian Methodist Episcopal Church in Montgomery. He soon became president of the Montgomery Improvement Association, at a time when white reaction to the civil rights movement in the South was most intense and violent, particularly in Alabama.

At the association, Mr. Douglas became a movement point person for logistics. Among other duties, he found lodging for visiting dignitaries — or sometimes just a bench in a church to sleep on. He rounded up a funeral-home limousine to take him and Dr. King on the 52-mile trip from Montgomery to Selma for strategy sessions, rallies and worship services.

The Selma-to-Montgomery marches he helped organize were crucial in mobilizing Congress to pass the Voting Rights Act, which President Lyndon B. Johnson signed into law on Aug. 6, 1965.

Mr. Douglas’s marriage to Blanche Gordon in 1962 ended with her death in 2015. In addition to his daughter, he is survived by two sons, Winston and Jesse Jr.; a brother, Collins; eight grandchildren; and three great-grandchildren.

Mr. Douglas’s work was widely admired among civil rights leaders.

“Dr. King had a great deal of faith in him,” Mr. Lewis told The Charlotte Observer in 2015. “He would say, ‘Jesse was taking care of this’ and ‘Jesse was taking care of that.’ And he could lead a song, creating a real sense of solidarity.”

Mr. Douglas’s singing became a huge part of his reputation.

“He really set the church on fire and got people motivated,” said Charles Steele Jr., a longtime president and chief executive of the Southern Christian Leadership Conference, “pretty much like Mahalia Jackson.”

In the 2018 interview, Mr. Douglas recalled how his pale skin had protected him from some of the fury of segregationists. “They always considered me a sympathizer with Black people, but not one of them,” he said. “You know, that’s how I became ‘unidentified white man.’ They didn’t want to arouse friction from their own kind for killing another white man.”

But there could be friction from fellow Black people, too, he said. “I had Black people make fun of me, call me ‘old white boy,’ ‘old albino,’” he said. “I never paid it any attention. I said, ‘If they’re dissatisfied with the way I look, go see God.’”

At the end of the march from Selma, he said, he was present for a rally at the Dexter Avenue Baptist Church in Montgomery, which had been Dr. King’s pulpit in the 1950s, and he thought, “Here at last! Here at last!” When Dr. King was assassinated three years later, Mr. Douglas preached a memorial service there.

The news of Dr. King’s death “struck me like somebody had taken a dagger and pierced me in the heart,” he said in an interview on the religious television show “The 700 Club.”

Mr. Douglas later served as a pastor at Christian Methodist Episcopal churches in Birmingham, Ala.; Kansas City, Mo.; Detroit; Chicago; Champaign, Ill.; and Flint, Mich., before retiring in 2004. He became a regular speaker at events celebrating Martin Luther King Jr. Day.

Mr. Steele of the Southern Christian Leadership Conference said Mr. Douglas was representative of the hundreds of people in the civil rights movement who toiled valiantly without much outside recognition.

“He had a beautiful personality, very outgoing, and everyone knew that if Dr. King or the national office needed something, he would do it,” Mr. Steele said. “You needed people like that — part of the inner circle, but someone willing to do whatever was needed to support the movement.”

Ash Wu contributed reporting.