Selma, which I have not seen yet, provides one moment in his life, showing how he was part of a movement. His letter from the Birmingham Jail is an example of his personal leadership role. He was in jail as part of a wider protest and years later his sentence was upheld (article on this matter) by the Supreme Court. It was left to the dissent to mention his name. Update: As noted in the article, confrontation was key to MLK's strategy. Thurgood Marshall used the courts. MLK's central concern was to force society to confront the injustice of their actions. A method that until today is controversial. See Garner et. al.