Mark Steven Kirk (born September 15, 1959) is an American politician. He was elected to the United States Senate for Illinois in 2010, but lost re-election in 2016. Before being a senator, Kirk represented the 10th congressional district of Illinois from 2001 to 2010.
On November 8, 2016, he was defeated in his bid for re-election to his U.S. Senate seat by Democrat Tammy Duckworth.