William Henry Frederick Fiedler (August 25, 1847 – January 1, 1919) was an American Democratic Party politician who represented New Jersey's 6th congressional district in the United States House of Representatives for one term from 1883 to 1885.

He attended the public and high schools, and apprenticed to the hat-finishing trade at the age of fifteen.

He was employed as a clerk and engaged in the retail hat and later in the men's clothing business.

He was elected an alderman of Newark in 1876 and 1878, and was a member of the New Jersey General Assembly in 1878 and 1879.

After leaving Congress, he was appointed postmaster of Newark on March 29, 1886, and served until October 1, 1889.