William Henry Harrison Flick (February 21, 1841 - June 7, 1904) was the author of the Flick Amendment, which removed voting restrictions on former Confederates. Flick was born in Cuyahoga County, Ohio. He served in an infantry regiment of the Union army during the Civil War, was wounded at the battle of Shiloh and discharged in 1862.

After studying law in Ohio, Flick opened a practice in Moorefield, Hardy County, in March 1866. The next year he moved to Franklin, Pendleton County, where he was elected prosecuting attorney. A Republican, Flick was elected to represent Pendleton and Grant counties in the West Virginia House of Delegates in 1868 and reelected in 1869.

He wrote what became known as the Flick Amendment to remove voting restrictions on former Confederates. The amendment, ratified in 1871, granted voting privileges to all male West Virginians who were not otherwise disqualified by age, mental condition or conviction of a felony. The amendment applied, as well, to former slaves, who were in any case enfranchised by the recently adopted 15th Amendment to the U.S. Constitution.

Flick was elected prosecuting attorney for Pendleton and Grant counties in 1872, resigned those positions in 1874, and relocated to Martinsburg, where he was an unsuccessful candidate for the West Virginia Supreme Court in 1876. Elected prosecuting attorney in Berkeley County in 1881, Flick resigned in 1882 upon his appointment as United States District Attorney for West Virginia. After leaving federal service, he returned to his law practice in Martinsburg. Flick was the Republican candidate for the U.S. House of Representatives in 1886 and 1888, losing both contests to William L. Wilson. From 1888 to 1893 he was postmaster in Martinsburg. He died in Martinsburg.