Ralph Engelstad (1930? Thief River Falls, Minnesota - November 26, 2002 Las Vegas, Nevada) was the multi-millionaire owner of the Imperial Palace Casinos in Las Vegas and in Biloxi, Mississippi and donor for the construction of the Ralph Engelstad Arena for his alma mater, the University of North Dakota, whose teams are called the Fighting Sioux.

Engelstad was a somewhat controversial figure, owing to his collection of Nazi memorabilia in the casino, including a painting of himself dressed in Nazi uniform. Also, as a condition of building the arena, Engelstad required that the Fighting Sioux name be kept indefinitely, despite the feelings of many in that native tribe.

Engelstad was known as a self-made man, and one of the very few independent casino owners in Las Vegas; he also was a great philanthropist, even aside from his work with the arena, but will probably not be remembered in a positive light.

Died 2002, after a lengthy battle with cancer.