Wisconsin Dells (formerly Kilbourn) is a city in Columbia, Sauk, Adams and Juneau counties in the U.S. state of Wisconsin. The population was 2,942 at the 2020 census. The city takes its name from the Dells of the Wisconsin River, a scenic gorge that features sandstone formations along the banks of the Wisconsin River. It is a popular Midwestern tourist destination, home to several water parks and tourist attractions. Wisconsin Dells is about 42 miles (68 km) northwest of Madison, the state's capital city.

The natural formation of the Dells was named by Early French explorers as dalles, a rapids or narrows on a river in voyageur French. Wisconsin Dells is located on ancestral Ho-Chunk and Menominee land. The Ho-Chunk name for Wisconsin Dells is Nįįš hakiisųc, meaning "rocks close together".

According to Indian agent Joseph Montfort Street, the Sauk leader Black Hawk sought refuge with Ho-Chunks near the Dells of the Wisconsin River at the end of the Black Hawk War of 1832 before surrendering to the United States, but more recent research has argued that this was a mistranslation of the true location. The U.S. acquired the land in treaties with the Ho-Chunk nation in 1837 and with the Menominee in 1848, but Ho-Chunk people who resisted the U.S. policy of Indian removal continued to return to the area and eventually acquired small homesteads.

The city of Wisconsin Dells was founded in 1856 by the Wisconsin Hydraulic Company, a dam-building and real estate investment business. The town was originally named Kilbourn City for Byron Kilbourn, the president of the La Crosse & Milwaukee Railroad Company, which was then preparing to build a railroad across the Wisconsin River to connect Milwaukee and La Crosse, Wisconsin. The railroad's route caused great local controversy. Boosters and speculators had anticipated the river crossing two miles downriver, where they had established the town of Newport, Wisconsin, and attracted around 1,500 residents by 1855. When the railroad instead completed a slightly more northern route in 1857, Newport rapidly turned into a ghost town as its residents relocated to the site of the railroad bridge, bringing many buildings and even a church from the earlier town to reassemble in Kilbourn City.

In 1859, lumbermen destroyed the Wisconsin Hydraulic Company's new dam at Kilbourn City because it blocked the flow of timber rafts down the river. This led the company's main creditor, Byron Kilbourn, to foreclose on its property and take ownership of most of the city's real estate.

According to the United States Census Bureau, the city has a total area of 8.18 square miles (21.19 km²), of which 7.84 square miles (20.31 km²) is land and 0.34 square miles (0.88 km²) is water. According to the Wisconsin Department of Administration, on January 19, 2004, the city annexed land from the Town of Lyndon in Juneau County, thus expanding the city to include area in four counties. It is mostly located in Columbia County.

Wisconsin Dells has a humid continental climate.

On July 13, 1936, the temperature in Wisconsin Dells reached 114 °F (46 °C), the highest ever recorded in the state of Wisconsin.