Louis Powell Harvey (July 22, 1820 – April 19, 1862) was an American politician and the seventh Governor of Wisconsin.

Harvey was born in East Haddam, Connecticut, later moving with his family to Ohio. He attended Western Reserve College and Preparatory School and worked as a teacher for a time, and eventually moved to Kenosha, Wisconsin, then named Southport, where he founded an academy. In Southport he associated with the Whig Party and edited a Whig newspaper, the Southport American (1843 – 1846).

In 1847, Harvey married Cordelia Perrine and they moved to Clinton, Wisconsin in Rock County, Wisconsin, then the nearby hamlet of Shopiere, Wisconsin. He helped organize the Republican Party, and was a Republican member of the Wisconsin State Senate from 1854 to 1858, Wisconsin Secretary of State from 1860 to 1862, and finally Wisconsin's governor in 1862.

In April 1862, having served only a few months as governor, Harvey organized an expedition to bring medical supplies to Wisconsin troops, wounded in the Battle of Shiloh, who were being cared for in hospital boats on the Mississippi and Tennessee Rivers. Harvey visited and cheered troops at Cairo, Illinois, Mound City, Illinois, and Paducah, Kentucky. Close to Shiloh, he stopped overnight near Savannah, Tennessee. Late that evening, while trying to step from a tethered boat to a moving steamboat headed back north (a common but dangerous practice), Harvey fell into the Tennessee River and drowned, despite the strenuous rescue efforts of members of his party.

His body was found 14 days later, 65 miles downstream; his remains lay in state in the Wisconsin State Capitol, and he was buried in Forest Hill Cemetery, in Madison. His wife Cordelia became a leading war nurse, honored with the rank of Colonel by Abraham Lincoln. She subsequently established veterans hospitals in Wisconsin, away from the war front, and a soldiers' orphans home.

Lieutenant Governor Edward Salomon succeeded Harvey.