Allen played a policeman in episode 1034 of DARK SHADOWS in 1970. In 1981, he guest starred on DALLAS as Lloyd Bettinger.
His recurring roles in television series include THE MARY TYLER MOORE SHOW, BAD NEWS BEARS (with Tricia Cast, Kristoff St. John and Kristoff St. John), HAPPY DAYS and BOSOM BUDDIES.
Allen studied at the Neighborhood Playhouse and starred in the Pulitzer Prize winning play "That Championship Season" and Albee's "Zoo Story", both of which he won best acting awards. He also performed in the controversial award-winning theatrical performance dealing with AIDS, "The Normal Heart." Phillip went on to do "Are You Now or Have You Ever Been?". The entire New York cast won an ensemble acting award.
His films included Onion Fields, Star Trek III, Mommie Dearest and Midway.
Survivors include Joanie, his wife, and devoted son Keegan who follows in his father's footsteps presently starring in the hit television series PRETTY LITTLE LIARS.