Östergötland Runic Inscription 166 (Ög 166) is a runestone located outside Skänninge in Mjölby Municipality. The stone stands erected at the ruins of a hospital chapel just northeast of the town. About a meter away stands another runestone, Östergötland Runic Inscription N272. Ög 166 is made of granite. The stone was once broken, and a piece is missing. The remaining parts have been rejoined using cement. "Bolde and Ulv raised these stones in memory of Trond and Farulv, their brothers."