British mariner and explorer of the Canadian plains who played a significant role in the establishment of the Hudson's Bay Company.

Kelsey was apprenticed to the Hudson's Bay Company (chartered 1670) by 1684, and in a trip to the region begun that year he conducted some exploration along the west shore of Hudson Bay. In 1689 he journeyed with a small party to the Churchill River area. Kelsey became proficient in Indian languages, and in 1690 he headed a company venturing ever farther westward to promote trade with the Indians and got to the Saskatchewan River and beyond. That two-year venture is believed to have made him the first white man to explore Canada's central plains. Twice, incursions by the French led to the capture of the western British outpost York Fort (now York Factory, Man.) while he was in the fort, and both times it was he who negotiated the surrender. For several years he was master of a frigate plying Hudson Bay in trade with Native Americans (First Nations). Kelsey was overseas governor of the Hudson's Bay Company from 1718 to 1722. Inexplicably, he wrote portions of many of his reports in rhyme.