Other contributors is the fourth core element. If someone other than the primary author (or editor) contributed to the source in a way that is relevant to your paper, you can identify that person by including this element (MLA 5.38-5.47).
Bradsher, Bethany. Super Bowl 50 : Celebrating Fifty Years of America's Greatest Game. Foreword by Dwight Clark, JKR Ventures, 2015.
Burton, Zisca. Bloom's How to Write About Toni Morrison. Introduction by Harold Bloom, Bloom's Literary Criticism, 2008.
Personal author(s) with editor(s):
Tynan, Kenneth. "The Kansas Farm Murders." The Critical Response to Truman Capote, edited by Joseph J. Waldmeir and John C. Waldmeir, Greenwood Press, 1999, pp. 129-34.
Personal author(s) with translator(s):
Kafka, Franz. The Metamorphosis. Translated by Stanley Corngold, 2013 ed., Modern Library, 1915.
Gorky, Maksim. Childhood. Translated by Margaret Wettlin, Oxford UP, 1961.
Multiple relevant contributors:
"Something Nice Back Home." Lost, directed by Stephen Williams, performance by Matthew Fox, season 4, episode 10, Bad Robot, 2008.
The information above is mostly adapted from IRSC Libraries.