Silas Moore Stilwell, Sr. (June 6, 1800 - May 16, 1881) was an American lawyer and politician.
He was born on June 6, 1800 in New York City, New York to Stephen Stilwell, who had fought in the American Revolutionary War and opened a glass factory in 1804 in .
Silas was educated at Woodstock Free Academy until 1812, then, after his father's bankruptcy, he went to New York City and began to work.
In 1814, he engaged in surveying in the west, and then settled in Tennessee. In 1822, he was a member of the Tennessee House of Representatives. Afterwards he removed to Virginia, and was Clerk of Tazewell County and a member of the Virginia House of Delegates. He was admitted to the bar in 1824.
He returned to New York in 1828, and was a member from New York County of the New York State Assembly from 1830 to 1833. In 1830, he proposed An act to abolish imprisonment for debt and to punish fraudulent debtors in the Assembly which was enacted on April 26, 1831, and became known as the Stilwell Act.
In 1834, he ran for Lieutenant Governor of New York on the Whig ticket with William H. Seward, but they were defeated. He was an alderman in New York City in 1835, and chosen chairman of the Board of Aldermen. In this year, the political parties were equally divided, and as he had the casting vote on all appointments he became popularly known as "King Caucus". He was acting mayor at the time of the Great Fire of New York in 1835.