Benjamin Dudley Dwinnell (September 14, 1834 - December 15, 1916) was an American law enforcement officer, military officer and politician who served as the nineteenth Sheriff of Worcester County, Massachusetts.

[1] Dwinnell was educated in the local public schools, after his education he worked for a year in the printing operations[1] of the National Eagle in Claremont, New Hampshire[2] after which Dwinnell moved to Worcester, Massachusetts where he worked in the grocery trade[2] and in a hardware store.

[1] In February 1864, after his enlistment in the 51st Regiment expired Dwinnell enlisted as a First Lieutenant and Quartermaster of the 2nd Regiment Massachusetts Volunteer Heavy Artillery, serving with Augustus B. R.

Having reached the rank of Brevet Major; Dwinnell was mustered out on September 23, 1865.

[1][2] After the American Civil War, Dwinnell returned to Worcester where he became the assistant Post Master under General Josiah Pickett.