Thomas Samuel Zilly (born 1935) is a United States federal judge.
Born in Detroit, Michigan, Judge Zilly received a B.A. from the University of Michigan in 1956 and a J.D. from Cornell Law School in 1962. He was a U.S. Naval Reserve Lieutenant (J.G.) from 1956 to 1962, serving on active duty from 1956 to 1959. He entered private practice in Seattle, Washington, working from 1962 to 1988. He was a Judge pro tem, Seattle Municipal Court, Washington from 1972 to 1980.
On February 16, 1988, Judge Zilly was nominated by President Ronald Reagan to a seat on the United States District Court for the Western District of Washington vacated by Walter T. McGovern. Zilly was confirmed by the United States Senate on April 19, 1988, and received his commission the following day. He assumed senior status on January 1, 2004.