Ansel Dyer Wass (November 12, 1832 – January 24, 1889) was a Union Army officer during the American Civil War.

[1] He enlisted as a first lieutenant on April 22, 1861 with the 6th Massachusetts Militia and served with that unit until the end of its term of service on August 2, 1861.

On October 14, 1863, was given temporary command of the 3rd brigade, 2nd division of the II Corps which he led during the Battle of Bristoe Station.

He was promoted to colonel and commanding officer of the 19th Massachusetts on February 28, 1864, a post which he held until the regiment was mustered out on July 28, 1864.

The regiment served first in Maryland to guard railroad lines and later was transferred to Indianapolis to deal with the threat of organized Confederate sympathizers in that region.