Terrence Leo O'Brien (born August 8, 1943)^[1] is a Senior United States circuit judge of the United States Court of Appeals for the Tenth Circuit.

O'Brien was born in Lincoln, Nebraska. He received a Bachelor of Science degree from the University of Wyoming in 1965. He received a Juris Doctor from University of Wyoming Law School in 1972. He was in the United States Army, Ordnance Corps from 1966 to 1969. He was a Staff attorney of Land & Natural Resources Division/Appellate Section, United States Department of Justice from 1972 to 1974. He was in private practice of law in Wyoming from 1974 to 1980. He was a District Judge, Sixth Judicial District Court of Wyoming from 1980 to 2000. He was a President, Visionary Communications, Inc. from 2000 to 2001. He was in private practice of law in Wyoming from 2001 to 2002.

O'Brien is a United States Circuit Judge of the United States Court of Appeals for the Tenth Circuit. O`Brien was nominated by President George W. Bush on September 4, 2001, to a seat vacated by Wade Brorby. He was confirmed by the United States Senate by a 98–0 vote on April 15, 2002.^[2] He received his commission on April 16, 2002.^[3] O'Brien assumed senior status on April 30, 2013.^[3]