is a Japanese clan which originates in Totomi Province. It was a retainer clan of the Imagawa family, and then switched sides to the Matsudaira clan of Mikawa Province. A famed 16th-century clan member, Ii Naomasa, served as one of Tokugawa Ieyasu's generals, and received the fief of Hikone in Omi Province as a reward for his conduct in battle at Sekigahara. The Ii and a few sub-branches remained daimyo for the duration of the Edo period. Ii Naosuke, the famed politician of the late Edo period, was another member of this clan.