William Harrison Dimmick (December 20, 1815 – August 2, 1861) was an American politician from Pennsylvania who served as a Democratic member of the U.S. House of Representatives for Pennsylvania's 13th congressional district from 1857 to 1861.

He studied law, was admitted to the bar in 1835 and commenced practice in Bethany, Pennsylvania.

He moved to Honesdale, Pennsylvania, in 1842 and continued the practice of law.

He served as prosecuting attorney of Wayne County, Pennsylvania, in 1836 and 1837.

[1] Dimmick was elected as a Democrat to the Thirty-fifth and Thirty-sixth Congresses.