John became interested in acting as a teenager and began attending dramatic school in Manhattan while still going to New Utrecht High School in Brooklyn. A photograph from a summer modeling job came to the attention of a Hollywood agent and thereafter luck, ability and the then prevailing Hollywood studio system provided John with a Universal Studios Stock Contract at seventeen, three weeks after his arrival in Los Angeles.
The next couple of years, while studying at the studio's acting school, were anxious and difficult, until roles came to prove to himself and others what he could do.
After much screen-testing John won a co-starring role with Esther Williams in the 1956 drama The Unguarded Moment. After that followed a series of young leading man roles in Rock Pretty Baby, Summer Love, The Restless Years, This Happy Feeling, andThe Reluctant Debutante. By 1958, John was a highly publicized "teenage heart throb" in movie magazines.
By 1960, however, John was doing character roles to explore his talent as an actor, in such films as Cry Tough, The Big Fisherman, The Unforgiven, The Plunderers, and Warhunt.
In 1961 his contract with Universal Studios ended and he went to Italy to try to promote a European acting career. After a year he returned to Los Angeles, concentrating on character acting, in scores of television shows.
In 1965 John won the role of Chuy Medina, a Mexican bandit, playing opposite Marlon Brando in The Appaloosa. John succeeded in winning good reviews and much attention for this protrayal.
A new contract with Universal led John to appear in many of the earliest feature length films made expressly for television, such as Doomsday Flight, Winchester 73, and The Bold Ones TV series.
In 1973 John co-starred in Enter the Dragon, with Bruce Lee, a film that has achieved cult classic status.
Recent years have been busy with features in the U.S. and abroad, as well as many televisions appearances, while John's off screen time these days is devoted to writing screenplays which he hopes to direct one day.
John has appeared in eighty feature films. The most recent being The Electric Horseman, Battle Beyond the Stars, Wrong Is Right, Nightmare on Elm Street 1 & 3, Fever Pitch, My Mom's a Werewolf, The Arrival, Aftershock, Cover-Up, Maximum Force, Jonathan of the Bears, Released to Kill, Beverly Hills Cop 3, and Nightmare on Elm Street 7.
His recent television appearances include Murder, She Wrote, and upcoming episodes of Melrose Place.
John has a twenty-three-year-old son named Antonio who recently graduated with honors from the University of California, and who has since begun to investigate the film business and acting.