James Shields (May 10, 1810 – June 1, 1879) was an American politician and United States Army officer who was born in Altmore, County Tyrone, Ireland. Shields, a Democrat, is the only person in United States history to serve as a U.S. Senator for three different states. Shields was a senator from Illinois 1849 to 1855, in the 31st, 32nd, and 33rd congresses, from Minnesota from May 11, 1858 to March 3, 1859, in the 35th congress, and from Missouri from January 27, 1879 to March 3, 1879, in the 45th congress.

Shields was the nephew of another James Shields, also born in Ireland, who was a Congressman from Ohio. The younger Shields immigrated to the United States around 1826 and settled in Kaskaskia, Randolph County, Illinois where he studies and later practiced law. He served as a member of the State House of Representatives, beginning to serve in 1836, and then as an Illinois Supreme Court justice and in 1839 as the state auditor. (He was elected when not yet a citizen; Illinois then required only that a legislator have been resident in the state for six months.)

Shields nearly fought a duel with Abraham Lincoln on September 22, 1842. Lincoln had published an inflammatory letter in a Springfield, Illinois, newspaper, the Sagamon Journal that poked fun at Shields, the State Auditor. Taking offense to the article, Shields demanded "satisfaction" and the incident escalated to the two parties meeting on a Missouri island called Sunflower Island, near Alton, Illinois to participate in a duel. Just prior to engaging in combat, the two participants' seconds intervened and were able to convince the two men to cease hostilities, on the grounds that Lincoln had not written the letters.