Thomas James O’Brien (July 30, 1842 – May 19, 1933) was a politician and diplomat from the U.S. state of Michigan.

On September 4, 1873, he married Delia Howard (July 14, 1848 - January 22, 1926).

In 1883 he was an unsuccessful candidate for the office of Justice of the Michigan Supreme Court.

O’Brien, a graduate of the University of Michigan law school, held the following posts as ambassador of the United States: O’Brien died on May 19, 1933.

[1] He is buried with his wife at Oakhill Cemetery in Grand Rapids, Michigan.