Mark Sorensen Jr. est né le 4 mars 1962 à Philadelphie, Pennsylvanie, États-Unis. Il était acteur. Il est connu pour Philadelphia (1993). Il est mort le 17 septembre 1993 à Pennsylvanie, États-Unis.
One of the many AIDS patients who appeared in Philadelphia (1993), he was staying at his parents' home when Jonathan Demme rushed him an unedited videotape of the movie during post-production; Sorensen died the following day. Tom Hanks paid tribute to him in his Golden Globe acceptance speech the following January.