William Cullen Crain (August 31, 1798, in Warren, Herkimer County, New York – March 16, 1865) was an American physician and politician.
His father was Rufus Crain, a physician, a judge of the Court of Common Pleas for sixteen years, and a near relative of General Israel Putnam.
Then he gave up the practice of medicine, and occupied himself with agriculture, his landed interests in Warren being considerable.
In 1826, he married Perses Narina Tunnicliff, daughter of William Tunnicliff, and granddaughter of the Count George Ernst August von Ranzau, an officer on the staff of the Friedrich Adolf Riedesel, and author of the interesting Journal of Burgoyne's Expedition contained in the archives of the general staff at Berlin.
He was a member from Herkimer County of the New York State Assembly in 1832, 1845 and 1846, and was Speaker in 1846.