Thomas Dyer (January 13, 1805 – June 6, 1862) served as mayor of Chicago, Illinois (1856–1857) for the Democratic Party.

[3] He was a meat-packing partner of former mayor John Putnam Chapin, who was one of Chicago's first meat packers.

Chapin built a slaughterhouse on the South Branch of the Chicago River in 1844.

[4] Running as a "pro-Nebraska" Democrat (aligned with Stephen A. Douglas, who publicly backed his candidacy), Dyer won the contentious 1856 Chicago mayoral election, defeating former mayor Francis Cornwall Sherman (who ran as an anti-Nebraska candidate).

[5][6] He died in Middletown, Connecticut on June 6, 1862, and was buried at Graceland Cemetery in Chicago.