Columbus (, kə-LUM-bəs) is the capital and most populous city of the U.S. state of Ohio. With a 2020 census population of 905,748, it is the 14th-most populous city in the U.S., the second-most populous city in the Midwest (after Chicago), and the third-most populous U.S. state capital (after Phoenix, Arizona, and Austin, Texas). Columbus is the county seat of Franklin County; it also extends into Delaware and Fairfield counties. The Columbus metropolitan area encompasses ten counties in central Ohio and had a population of 2.14 million in 2020, making it the largest metropolitan area entirely in Ohio and 32nd-largest metro area in the U.S.

Columbus originated as several Native American settlements along the Scioto River. Franklinton, now a city neighborhood, became the first European settlement in 1797. The city was founded in 1812 at the confluence of the Scioto and Olentangy rivers and was planned as the state capital. Named after Italian explorer Christopher Columbus, it assumed the role of capital in 1816 and became the county seat in 1824. Despite periods of flooding and economic downturns, the city grew steadily through industrialization. Beginning in the 1950s, Columbus experienced rapid expansion, becoming Ohio's largest city by land and population by the early 1990s. Growth has continued into the 21st century, with major redevelopment in neighborhoods across the city, including downtown.

Columbus has a diverse economy. The metropolitan area is home to the Battelle Memorial Institute, the world's largest private research and development foundation; Chemical Abstracts Service, the world's largest clearinghouse of chemical information; and the Ohio State University, one of the largest universities in the United States. The Greater Columbus area is further home to the headquarters of Fortune 500 companies Cardinal Health, Nationwide, American Electric Power, Huntington Bancshares and Vertiv. It hosts cultural institutions such as the Columbus Museum of Art, COSI, Franklin Park Conservatory and Ohio Theatre. The city's major league professional sports teams include the Columbus Blue Jackets (NHL) and Columbus Crew (MLS).