Robert van Rensselaer (December 16, 1740 – September 11, 1802) was Brigadier General during the American Revolutionary War, a member of the New York Provincial Congress from 1775 to 1777 and later a member of the New York State Assembly in the 1st, 2nd and 4th New York State Legislatures.
Robert van Rensselaer was born December 16, 1740, at Fort Crailo in Rensselaer, New York to Johannes van Rensselaer (1708–1793), and Engeltie "Angelica" Livingston (1698–1746/47). His grandfather was Hendrick van Rensselaer (1667–1740), director of the Eastern patent of the Rensselaerswyck manor, and his paternal grandmother was Catharina Van Brugh, daughter of merchant Johannes Pieterse Van Brugh (1624–1697). His older siblings were Jeremiah Van Rensselaer (1738–1810) and Catherine van Rensselaer (1734–1803) who in 1755 married Philip Schuyler (1733–1804), a Revolutionary general and later a United States Senator from New York.
On October 20, 1775, he was made colonel of the 8th Albany County Regiment of militia and on June 16, 1780, he was promoted to brigadier general of the second brigade of the Albany County militia. This brigade included the Tryon County militia. He fought at Fort Ticonderoga and at the Battle of Klock's Field.