Michael Bert Thornton (born February 9, 1954) is an American lawyer who serves as a senior judge of the United States Tax Court.

[1] He graduated summa cum laude from the University of Southern Mississippi with a Bachelor of Science in accounting in 1976.

He served as law clerk to Charles Clark, chief judge for the United States Court of Appeals for the Fifth Circuit from 1983 to 1984.

He has served as Chief Judge since 2012 (save for the period from March 8 through August 6, 2013).

He was subsequently renominated by President Barack Obama on May 9, 2013, for an additional fifteen-year term, which was confirmed by the Senate on August 1, 2013.