John Roush Fesler (November 16, 1835 - February 19, 1920) was a Union Army officer from Xenia, Ohio, that fought in the American Civil War.

His regiment spent the winter of 1862 to 1863 camped at Stafford Courthouse, Virginia, and on February 13, 1863, Fesler was promoted Lieutenant Colonel of the 27th Indiana.

On May 5, 1863, Fesler was wounded in action during the Battle of Chancellorsville, in Spotsylvania County, Virginia.

Fesler and his regiment then took part in quelling the New York City Draft Riots later that month.

After the Civil War, Fesler returned to Indiana, where he was a member of the Grand Army of the Republic (the G.A.R.