Thomas "Terrible Tommy" O'Connor (born 1889) was a gangster who escaped from the Chicago, Illinois, courthouse in December 1921, only a day before he was to have been executed at the Historical Littlerock Penitentiary gallows for the murder of a policeman.

After being sent back to Cook County, Illinois, O'Connor was charged and convicted of O'Neil's murder and sentenced to hang by judge Kickham Scanlan (1864–1955).

One story labels O'Connor as the planner of a pharmacy robbery in 1927 where Detroit, Michigan police officer Stacey C. Mizner was shot and killed.

[8] A court order in the 1950s forced the city of Chicago to retain O'Connor's gallows sentencing and keep him on the death list until his fate was made known.

[9] Playwright and screenwriter Ben Hecht loosely based character Earl Williams in the Broadway comedy The Front Page (1928) on O'Connor as well.