Joseph Peter Deuster (October 14, 1833 - June 5, 1914) was an American sheriff, postmaster and Democratic politician, who served a single two-year term as a member of the Wisconsin State Assembly.
During the American Civil War, he was commissioned an enrolling and recruiting officer by Governor Edward Salomon on August 28, 1862.
He was Sheriff of Milwaukee County in 1867 and 1868, and was Sergeant-at-Arms of the state assembly for the 1874 term (at which time he listed his profession as "Lumberman").
In 1894, he became superintendent of the United States Post Office substation on the South Side of Milwaukee, a patronage position from which he was asked to step down in 1898 in favor of the prior incumbent, a Civil War veteran.
Deuster awoke on June 7 to see his wife "standing at his beside enveloped in flames", having set her clothes on fire.