Thomas Newman O'Neill Jr. (born 1928) is a United States federal judge.
Born in Hanover, Pennsylvania, O'Neill was in the U.S. Naval Air Reserve from 1948 to 1953. He received an A.B. from Catholic University of America in 1950 and an LL.B. from the University of Pennsylvania in 1953. He was a law clerk to Judge Herbert F. Goodrich, U.S. Court of Appeals, Third Circuit from 1953 to 1954, and to Justice Harold H. Burton, Supreme Court of the United States from 1954 to 1955. He was a Fulbright scholar, London School of Economics from 1955 to 1956. He was in private practice in Philadelphia, Pennsylvania from 1956 to 1983.
O'Neill was a federal judge on the United States District Court for the Eastern District of Pennsylvania. O'Neill was nominated by President Ronald Reagan on June 21, 1983, to a seat vacated by Edward R. Becker. He was confirmed by the United States Senate on August 4, 1983, and received his commission on August 5, 1983. He assumed senior status on July 6, 1996.