Penn Grossman was a male Human of East Asian descent, and a student at Berkeley University in the late 2260s. He was a member of the anti-Prime Directive organization Students for Stars for the People, and the partner of the group's leader, Marita Llorente. Grossman was a nervous and pessimistic individual, and when former Starfleet officer Spock approached their group for help following the Talin IV disaster, Grossman questioned his motives and resented his overshadowing of SSP's other members. (TOS novel: Prime Directive)

Grossman may have been the father of Llorente's infant son, Alexander, though this is never explicitly stated.