Series 4 contains photographs of Eugene O'Neill, Carlotta O'Neill, Oona Chaplin, and other family, as well as actors and others associated with O'Neill and his productions. Individuals in photographs include: Kathryne Radovan Albertoni, Fay Bainter, Ralph Barton, Ingrid Bergman, Travis Bogard, Edwin Booth, Annie Chaplin, Charlie Chaplin, Geraldine Chaplin, Josephine Chaplin, Michael Chaplin, Cynthia Chapman, Melvin Chapman Jr. and Sr., Oona Chaplin, Ilka Chase, George M. Cohan, Clifford L. Feiler, Herbert Freeman, Ben Gazzara, Helen Hays, Robert Edmond Jones, Mabel E. Kuss, Cloris Leachman, Jo Mielziner, Leon Mirlas, Agnes Boulton Burton O'Neill, Carlotta Monterey O'Neill, Eugene O'Neill, James O'Neill, Mary Ellen Quinlan O'Neill, Shane O'Neill, Jack Raleigh, Jason Robards, Louis Scheaffer, Frances Steloff, Nellie Tharsing, etc. Photographers include P.W. Griffiths, Jere Hageman, Nickolas Muray, Ben Pinchot, Carl Van Vechten, etc. A small number of negatives are included. 274 items.

Additional photographs can be found in Series 5 and 6.