William Larimer, Jr. (1809-1875) was a American settler and land developer. He is most famous as the founder of Denver, Colorado in 1858. Larimer often went by "General Larimer", having acquired the title in the Pennsylvania Militia .

Larimer was born in Pittsburgh. He became in a land speculator in the 1850s in the Kansas Territory, founding a homestead in Leavenworth where he lived with his wife and nine children. In 1858 Larimer helped found the Denver City Land Company with the intention of creating a new city in the western part of the territory. Larimer arrived in the western part of the territory and staked a claim on square-mile parcel on a hill overlooking the confluence of Cherry Creek and the South Platte River. The site was across Cherry Creek from the existing settlement of Auraria. Larimer staked his claim by laying cottonwood logs along the hill on November 22. Larimer chose the name "Denver City" to honor the governor of the Kansas Territory, James W. Denver, with the intention that the city would become the county seat of Arapaho County.

Larimer plated the site and aggressively sold tracts to miners and other emigrants arriving along the Rocky Mountains. In the first years, tracts were often trading for grubstakes and in gambling. Denver emerged over its rival Auraria when the founders of Auraria, who were from Georgia, returned to the South to fight for the Confederacy at the outbreak of the American Civil War.

Larimer died in 1875 in Leavenworth, Kansas. He is commerorated in the city be founded by Larimer Street in downtown, as well as Larimer Square . He is also commemorated by Larimer County, Colorado in the northern part of the state.