John Eric Ensign (born March 25, 1958) is a former United States Senator from Nevada, serving from January 2001 until he resigned amid an investigation of ethics violation in May 2011. He is a member of the Republican Party and the former chairman of the Senate Republican Policy Committee.
Ensign was born in Roseville, California, to Sharon Lee Cipriani and a father whose surname was Mueller; his maternal grandfather was of Italian descent. Ensign says that he is one eighth (1/8) Filipino American, his Philippine-born paternal grandfather having been half-Filipino and half-German. Ensign's family moved to Nevada when he was a child. His mother remarried Michael S. Ensign, a gaming industry executive who subsequently became chairman of the board of directors of Mandalay Bay, and who adopted John.
Ensign attended the University of Nevada, Las Vegas, becoming a member of the Sigma Chi fraternity, and later graduated from Oregon State University with a Bachelor of Science degree in 1981. He went on to receive his Doctor of Veterinary Medicine degree from the Colorado State University in 1985 and entered veterinary practice soon after. He then became a successful businessman, opening a 24-hour animal hospital in Las Vegas. He owned two animal hospitals before entering politics.