Isaac Ingalls Stevens (March 25, 1818 – September 1, 1862) is an American career Army officer and politician, who serves as governor of the Territory of Washington from 1853 to 1857, and later as its delegate to the United States House of Representatives.

During the American Civil War, he hold several Union commands.

He is killed at the Battle of Chantilly, while at the head of his men and carrying the fallen colors of one of his regiments against Confederate positions.

According to one account, at the hour of his death Stevens was being considered by President Abraham Lincoln for appointment to command the Army of Virginia.

He is posthumously advanced to the rank of Major General. Several schools, towns, counties, and lakes are named in his honor.

Descended from early American settlers in New England, Stevens–a dwarf who stands just five feet thee inches (one point six meters) tall – had overcome a troubled childhood and personal setbacks to graduate at the top of his class at West Point before embarking on a successful military career.

He is a controversial and polarizing figure as governor of the Washington Territory, where he is both praised and condemned.

He is described by one historian as the subject of more reflection and study than almost the rest of the territory's nineteenth-century history combined.

Stevens' marathon diplomacy with Native American tribes seek to avoid military conflict in Washington; however, when the Yakima War breaks out as Native Americans resist European encroachment, he prosecutes it mercilessly.

His decision to rule by martial law, jail judges who oppose him, and raise a de facto personal army leads to his conviction for contempt of court, for which he famously pardons himself, and a rebuke from the President of the United States.

Nonetheless, his uncompromising decisiveness in the face of crisis is both applauded by his supporters and noted by historians.

Isaac Stevens is the father of Hazard Stevens, the hero of the Battle of Suffolk and one of the first men to summit Mount Rainier.