Henrik Klasson Horn af Kanckas (c.1512–1595) was a Swedish army commander, officer and gentleman of Kanka. He was the son of the Privy Councillor Klas Henriksson Horn and his second wife Kristina, and cousin of the commander Klas Kristersson Horn.
Henrik Klasson Horn worked under Gustav Vasa and his two oldest sons Erik XIV and John III (who ruled Finland under the title of Duke John). He became chief judge in southern Finland during 1549 – 1561. He was also appointed governor of Finland in 1551. In 1555 Henrik Klasson Horn participated in the campaign against Nöteborg.
Between 1558 and 1563 Horn was one of Duke John's closest advisers. Horn then served under King Erik XIV, and was made a colonel in the Livonian War in October 1563. In 1565 Horn became governor of Reval and over Livonia. After commendable activity in Estonia, he lost command in 1567 after the failure of the Swedish siege of Narva in 1579, and was replaced by Pontus de la Gardie.[1]