Dierkes was born on February 10, 1905, in Cincinnati, Ohio. He attended Brown University and subsequently went to work as an economist for the United States Department of State. In 1941 he joined the Red Cross and served in Britain during World War II. There he met director John Huston who recommended that he try Hollywood after the war. Instead, Dierkes went to work for the U.S. Treasury Department which coincidentally sent him to Hollywood to function as technical advisor for the film To the Ends of the Earth (1948) and Orson Welles cast him as Ross in his version of Macbeth in the same year. Welles used Dierkes again in his Touch of Evil (1958). He married Cynthia Dierkes and they had two daughters and two sons.

Because of his appearance and very tall frame (6 ft 6 in), Dierkes enjoyed a long career as a character actor, often portraying either villains or soldiers. One noteworthy performance cast Dierkes as the compassionate and caring scientist Dr. Chapman in the 1951 film The Thing from Another World which remains a mainstay science fiction classic of the 1950s. His performance provided sanity and calm amid the tension and chills of the action thriller. Although playing against type, his low tone and measured monotone dialogue was a good counter to the rapid and chaotic overlapping dialogue throughout the movie, giving brief pauses between each actor's lines as the tension in each scene increased. In 1951 he played a soldier next to Audie Murphy in the classic film, Red Badge of Courage, using that same soft tone. In the 1953 film Shane, Dierkes portrays the callous Morgan Ryker with great effect, director George Stevens making good use of Dierkes' craggy features. Alongside his 'brother' Rufus (Emile Meyer) and Jack Wilson (Jack Palance) he completes a trio of villains who are dispatched by the title character, Shane, in the final bar room shootout. One of his more memorable scenes is in the 1960 film, The Alamo. Dierkes portrays a Tennessean named Jocko, who is torn between leaving before the attack to care for his blind wife, or staying to support the Texans' cause. Understanding that if Jocko stays to fight she will likely be widowed, Jocko's wife coaxes him to stay and defend the fort, despite her disability.

His other film credits included The Naked Jungle (1954), The Raid (1954), Jubal (1956), The Daughter of Dr. Jekyll (1957), Blood Arrow (1958), The Left Handed Gun (1958), The Buccaneer (1958), The Hanging Tree (1959), The Oregon Trail (1959), One-Eyed Jacks (1961), The Premature Burial (1962), X: The Man with the X-ray Eyes (1963), The Haunted Palace (1963), The Omega Man (1971) and Rage (1972).

He appeared on the television screen on Gunsmoke, as "Mr. Rydell" in the 1956 episode "The Roundup" (S2E4) and as "Ace" in the 1957 episode "Gone Straight" (S2E20) and as "Indian" in the 1971 episode "My Brother's Keeper" (S17E10).

Dierkes died on January 8, 1975, from emphysema in Los Angeles, California.

• John Dierkes at IMDb