Hendrick Theyanoguin (c. 1691 – September 8, 1755), whose name had several spelling variations, was an important Mohawk leader and member of the Bear Clan; he resided at Canajoharie or the Upper Mohawk Castle in colonial New York. He was a Speaker for the Mohawk Council. Hendrick formed a close alliance with Sir William Johnson, the Superintendent of Indian affairs in North America.
Until the late 20th century, Hendrick's biography was conflated with an older Mohawk leader given the same first name in baptism, Hendrick Tejonihokarawa (also known as Hendrick Peters) (c. 1660 – c. 1735). The latter was a member of the Wolf Clan (an important difference, as shown by the historian Barbara Silvertsen) and based in Tiononderoge, the Lower Castle, closer to the English base in Albany. He was one of the "four Indian kings" who visited England and Queen Anne in 1710. The English built Fort Hunter in Tionondaga in 1711 with an Anglican mission. The Mohawk village became mostly Christianized early in the eighteenth century.
Theyanoguin was born to a Mohawk woman and a Mohegan man in Westfield, Massachusetts. By the Mohawk matrilineal kinship system, he was considered born into his mother's Bear Clan. Hereditary offices and property are passed through the maternal line and the mother's oldest brother plays a prominent role in her children's lives, especially for boys. The uncle is more important than the biological father. This system allowed the Mohawk to adopt and assimilate war captives into the tribe, absorbing them as Mohawk. Theyanoguin was baptized as "Hendrick" by Godfridius Dellius of the Dutch Reformed Church in 1692. The English referred to him as Hendrick Peters or King Hendrick.
At some point, Theyanoguin resettled at Canajoharie, one of two major Mohawk towns by the early 18th century. Both were located on the south side of the Mohawk River. European colonists referred to it as the "Upper Castle", in the Mohawk River valley upriver and west of Schenectady. Theyanoguin became a chief of the Mohawk Bear clan and would have participated in the Mohawk Council. He was not one of the fifty League sachems of the Iroquois Grand Council, made up of representatives of the Five Nations (six, after the Tuscarora were admitted in 1722).