Thomas Glenn Langan spent most of his early life in his home town of Denver, Colorado. After completing his education he acted in local repertory companies before moving to New York. In 1942, he appeared on Broadway opposite Luise Rainer in J.M. Barrie's "Kiss for Cinderella". He garnered good critical reviews which led to a contract with 20th Century Fox the following year. With many top leading men of the era away on wartime duties, the tall, muscular Langan filled the gap in several A-grade productions.

Langan was usually seen in the role of the stalwart professional man, appearing to best advantage as a French professor in the romantic Margie (1946), a devoted young doctor protecting Gene Tierney from the evil machinations of Vincent Price in Dragonwyck (1946), and as one of the psychiatrists looking after demented patient Olivia de Havilland in the The Snake Pit (1948). Langan was also gainfully employed in escapist adventure, essaying a square-jawed privateer captain in Forever Amber (1947) and starring as Edmund Dantes -- descendant of the original protagonist of Alexandre Dumas -- in the updated and modernised, Treasure of Monte Cristo (1949).

In spite of these boosts to his career, his sturdy good looks and rugged appeal, Langan's popularity gradually waned by the early 1950s. He spent the next decade appearing on various television episodes and eventually achieved a kind of cult status as the irradiated 60-foot hero of Bert I. Gordon's often hilarious schlock sci-fi The Amazing Colossal Man (1957). After winding down his screen career in the 60s, Langan re-invented himself as a successful real estate salesman. He was married for forty years to the actress Adele Jergens.