Robert Horace Chamberlain (June 16, 1838 – June 28, 1910) was an American law enforcement officer, machinist, military officer and politician who served as the eighteenth Sheriff of Worcester County, Massachusetts.

[5] When the Civil War broke out, he enlisted in the 51st Massachusetts Infantry Regiment, and was promoted from private to sergeant.

He reenlisted in the 60th Regiment and was commissioned captain of Company F.[5] He went on to serve as a brigadier general in the Massachusetts militia until 1876.

[6] On January 10, 1865[3][4] Chamberlain married Esther Browning of Hubbardston, Massachusetts, they had two daughters – Flora B.

[2][7] In the fall of 1891, Chamberlain, after winning a lively caucus, was elected Worcester County Sheriff.