Sylvester Gardner Hill (1820-1864) was a colonel in the Union Army during the American Civil War.

He served as a brigade commander during the Red River Campaign and Battle of Nashville where he was killed in action.

Hill helped raise the 35th Iowa Volunteer Infantry Regiment, of which he was appointed Colonel on September 18, 1862.

[3] For the first several months of its existence the 35th Iowa was on garrison duty in Illinois and Kentucky until being ordered to join the Army of the Tennessee besieging Vicksburg.

[4] After the siege of Vicksburg, Colonel Hill assumed command of the 3rd Brigade, 1st Division, XVI Corps (Right Wing), a position he would maintain for much of the remainder of the war.