Gregory Harrison was born on Santa Catalina Island, California in the resort city of Avalon. Harrison’s first big break came in 1976, when he was cast in a guest-starring role in the CBS series "M*A*S*H." That was followed by roles in "Barnaby Jones" and the TV movie "Trilogy Of Terror" with Karen Black. In 1977, Harrison landed the title role in the science-fiction TV series "Logan's Run." The series was cancelled after one season, but Harrison was finally becoming an established leading man.
Shortly after, Harrison was cast in the Christmas TV Movie "The Gathering," which was the first of many times he would work with Stephanie Zimbalist. After it won the Emmy® for best movie of the season, it also led to his biggest break, the 1978 mini-series "Centennial," in which he had the central role of Levi Zendt.
Harrison was soon cast in CBS’s "Trapper John, MD" in 1979 as Dr. Gonzo Gates. Eventually, Harrison directed eight of the later episodes of the show, but halfway through its seventh and final season, he moved on. In 1980 he formed, with Franklin R. Levy, the Catalina Production Group. Over the next eleven years, they produced numerous stage projects and nearly two dozen television movies.
Catalina Productions was an important force in the Los Angeles theater scene from 1981 to 1992 and plays presented by the company were honored with over 150 local theater awards. Those plays included "The Hasty Heart," which won the Los Angeles Drama Critics Award as Best Production (including Best Actor for Gregory) and "Picnic," for which Gregory won a Dramalogue Award. In 1990, he was supremely honored with a L.A. Ovation Award for Outstanding Contribution to L.A. Theater.
Harrison is married to former "CHiPs" actress Randi Oakes. The couple has three girls and a boy: Emma, Lily, Kate, and Quinn. They currently reside in southern Oregon.