Stevens Thomson Mason (October 27, 1811January 4, 1843) was an American politician who served as the 1st Governor of Michigan from 1835 to 1840. Coming to political prominence at an early age, Mason was appointed his state's acting Territorial Secretary by Andrew Jackson at 19, becoming the acting Territorial Governor soon thereafter in 1834 at the age of 22. As territorial governor, Mason was instrumental in guiding Michigan to statehood, which was secured in 1837. A member of the Democratic Party, he was elected as Michigan's first state Governor in 1835, where he would serve until 1840. Elected at age 23 and taking office at 24, Mason was and remains the youngest state governor in American history as of 2016.