Thomas J. Walsh (June 12, 1859 - March 2, 1933) was a lawyer and Democratic Party politician from Helena, Montana in the United States. He represented Montana in the United States Senate from 1913 until 1933. He helped expose the Teapot Dome Scandal, opposed child labor, and supported the right of women to vote.
Walsh was born in Manitowoc County, Wisconsin.
Walsh was named to the post of Attorney General by the incoming President Franklin Delano Roosevelt, but he died on a train near Wilson, North Carolina while traveling to Washington, D.C.