Among his other well-known roles were Dr. Gillespie in the NBC television series Dr. Kildare (1961–1966), John Brown in Santa Fe Trail (1940) and Seven Angry Men (1955), Abraham Farlan in A Matter of Life and Death (1946), and Jonathan Brewster in Arsenic and Old Lace (1944).

Lieutenant Massey returned to Canada after being wounded at Zillebeke in Belgium during the Battle of Mont Sorrel in 1916 and was engaged as an army instructor for American officers at Yale University.

[4][5][6] In 1918, he was recalled to active service and joined the Canadian Siberian Expeditionary Force that went to Siberia during the Allied intervention in the Russian Civil War.

On the orders of his commanding general, he organized a minstrel show troupe with himself as end man in blackface to bolster morale of allied troops on occupation duty in Vladivostok.

[4] In 1942, during World War II, Massey rejoined the Canadian Army and served as a major in the adjutant general's branch.

[4] The Washington Post credited him with performances in over 80 plays, including Pygmalion with Gertrude Lawrence; Ethan Frome with Ruth Gordon; and the George Bernard Shaw works The Doctor's Dilemma and Candida with Katharine Cornell.

In 1944, Massey played the district attorney in Fritz Lang's classic film noir The Woman in the Window, which starred Edward G. Robinson and Joan Bennett.

"[9] His preparation for the role was so detailed and obsessive that one person commented that Massey would not be satisfied with his Lincoln impersonation until someone assassinated him.

During World War II, he teamed up with Katharine Cornell and other leading actors in a revival of Shaw's Candida to benefit the Army Emergency Fund and the Navy Relief Society.

He was cast in 1960 as Sir Oliver Garnett in the episode "Trunk Full of Dreams" of the NBC series Riverboat.

His high-profile estrangement and divorce from Adrianne Allen was the inspiration for Ruth Gordon's and Garson Kanin's script for the film Adam's Rib (1949), starring Katharine Hepburn and Spencer Tracy, and indeed Massey married the lawyer who represented him in court, Dorothy Whitney, while his then former wife, Allen, married the opposing lawyer, William Dwight Whitney.

Massey also dabbled in politics, appearing in a 1964 television advertisement in support of the conservative Republican presidential nominee Barry Goldwater.