William Butler (December 2, 1822 – November 2, 1909) was a United States federal judge.
Born in Chester County, Pennsylvania, Butler read law to enter the bar in 1845. He was in private practice in West Chester, Pennsylvania, and was district attorney of Harrisburg, Pennsylvania from 1856 to 1859. He was a presiding judge of the Court of Common Pleas in Harrisburg from 1861 to 1879.
On February 12, 1879, Butler was nominated by President Rutherford B. Hayes to a seat on the United States District Court for the Eastern District of Pennsylvania vacated by John Cadwalader. Butler was confirmed by the United States Senate on February 19, 1879, and received his commission the same day. Butler served in that capacity until his retirement from the bench on January 31, 1899.
He died in Chester County, Pennsylvania.