The recent publication of Harper Lee’s “Go Set a Watchman” has left many fans of her 1960 novel “To Kill a Mockingbird” disillusioned. Some who regarded “Mockingbird”’s central character Atticus Finch as a moral paragon fighting Southern racism have been deeply disappointed by “Watchman” (actually an earlier draft of “Mockingbird”), in which Atticus is rendered as a racist curmudgeon.

Readers unhappy about losing a fictional Atticus might, however, reclaim the “real” one. Gregory Peck, who so famously embodied Atticus in the film version of “Mockingbird,” passionately opposed racial prejudice. And now, unpublished documents in the Margaret Herrick Library (the Oscars archive) reveal Peck’s personal opposition to racism, long before Harper Lee even wrote “Mockingbird.” The young actor attacked bigotry against both blacks and Jews.

Peck expressed some of his earliest anti-racist views with regard to Haiti. The U.S. had occupied Haiti from 1915 to 1934, and Hollywood films from the era depicted the country as a land of bizarre “voodoo” rites and zombies. However, Peck had visited the country in the 1940s, and when Darryl Zanuck of Fox Studios sought to persuade him to star in “Lydia Bailey,” an adventure-romance set during the Haitian Revolution (1791–1804), Peck asked to make a more serious film about Haiti.

He wanted to highlight the egalitarian ideals of Haiti’s revolution, in which African slaves had successfully revolted and made their country the first free black republic in the Americas. Peck likened Haitians’ fight for independence to the American Revolution. He spoke of how Haitian revolutionaries “carried on democratic ideals… against all the efforts of the French to retake the island and continue the exploitation of the people, their former slaves.” Peck compared the suffering of Haitians and “the poor negroes in the [American] South,” who he felt were even worse off.

Peck also denounced anti-Semitism, most notably through his role in the 1948 film “Gentleman’s Agreement.” It is easy today to forget the strength of anti-Semitism in the U.S. before the 1960s, where Jews faced widespread discrimination in housing and the workplace, as well as at prestigious universities and resorts. Anti-Semites such as Congressman John Rankin of Mississippi even used the word “kike” on the House floor. Though many Jewish studio executives were afraid to acknowledge the problem, for fear of a backlash, Daryl Zanuck, one of Hollywood’s few non-Jewish studio heads, decided to tackle the subject. He sought to turn Laura Hobson’s 1946 novel “Gentleman’s Agreement” into a film, personally entrusting the story to Peck. Peck’s stirring portrayal of Phil Green, a gentile journalist who goes undercover to expose everyday anti-Semitism, has become legendary. The role earned Peck an Oscar nomination. ...