Sir William Johnson, 1st Baronet (c.1715—11 July 1774) was an Irish official of the British Empire. As a young man, Johnson moved to the Province of New York to manage an estate purchased by his uncle, Admiral Peter Warren, which was located amidst the Mohawk, one of the Six Nations of the Iroquois League. Johnson learned the Mohawk language and Iroquois customs, and was appointed the British agent to the Iroquois. Because of his success, he was appointed in 1756 as British Superintendent of Indian Affairs for the northern colonies. Throughout his career as a British official among the Iroquois, Johnson combined personal business with official diplomacy, acquiring tens of thousands of acres of Native land and becoming very wealthy.
Johnson commanded Iroquois and colonial militia forces during the French and Indian War, the North American theatre of the Seven Years' War (1754–1763) in Europe. His role in the British victory at the Battle of Lake George in 1755 earned him a baronetcy; his capture of Fort Niagara from the French in 1759 brought him additional renown. Serving as the British Superintendent of Indian Affairs for the northern district from 1756 until his death in 1774, Johnson worked to keep American Indians attached to the British interest.
His counterpart for the southern colonies was John Stuart.
William Johnson was born around 1715 in County Meath, in the Kingdom of Ireland. He was the eldest son of Christopher Johnson (1687–1764) of Smithstown, Co. Meath and Anne Warren, daughter of Michael Warren of Warrenstown, Co. Meath and Catherine Aylmer, sister of Admiral Matthew Aylmer, 1st Baron Aylmer.