Sidney Poitier was an electrifying presence on-screen. In life, he used his charisma and his renown as forces for change.

The actor best known for history-making roles in such films as “Guess Who’s Coming to Dinner,” “In the Heat of the Night” and “Lilies of the Field” made immense contributions to the civil rights movement. Dr. Russell Wigginton, president of the Memphis-based National Civil Rights Museum, points to Poitier’s staunch support of Martin Luther King Jr. and the actor’s participation in the 1966 March Against Fear through one of Mississippi’s most deeply segregated regions.

Poitier, who died Jan. 6 at the age of 94, worked his way up an overwhelmingly white industry by playing against type. He famously refused to take on stereotypical roles for a Black male actor. With his talent and his tenacity, Poitier built bridges and opened doors for so many. At the same time, he was dedicated to civil rights.

He was there on the steps of the Lincoln Memorial in Washington, D.C., during the March on Washington on Aug. 28, 1963. He witnessed King delivering his historic “I Have a Dream” speech.

Such was Poitier’s contribution and legacy that the National Civil Rights Museum honored him with its Freedom Award in 2001.

“Despite his celebrity, he did what he believed in because he felt it was the right thing to do. He did not seek or need outward reinforcement or attention or accolades for doing the right thing,” Wigginton says. Poitier dedicated much of his resources and presence to Mississippi in the 1960s because the state was a hotbed of segregation and exploitation of Black residents.

“He understood the significance of him being in Mississippi and being with Dr. King. For somebody who had so much limelight, he didn’t seem to share that as much as doing the principled, important work of setting an example and showcasing to the world that this is what he stood for,” Wigginton says.

King and Poitier had many common bonds, including the burden of celebrity. “Everything they did was being monitored observed and meaning made from,” Wigginton says. “Being together allowed them to kind of relax in a way that they probably couldn’t around a lot of people and to have untethered conversation and share their deepest thoughts about the world and their purpose.”

Poitier’s activism filtered into his art. In Norman Jewison’s taut 1967 drama “In the Heat of the Night,” Poitier’s Virgil Tibbs delivered a slap to Larry Gates’ racist plantation owner Mr. Endicott that had a huge impact on the country. As Poitier recalled in his 2000 memoir “The Measure of a Man,” the initial version of the scene was quite different. “In the original script, I looked at him with great disdain and, wrapped in my strong ideals, walked out,“ he wrote. “That could have happened with another actor playing the part, but it couldn’t happen with me.”

Back in 1967, King noted Poitier’s contributions, calling him “a man of great depth, a man of great social concern, a man who is dedicated to human rights and freedom.”