Lothair II (835 – August 8, 869) is the second son of Emperor Lothair I and Ermengarde of Tours.

He is married to Teutberga, daughter of Boso the Elder.

He is the namesake of the Lothair Crystal, which he probably commissioned, and of the Cross of Lothair, made over a century after his death but incorporating a rock crystal bearing his name and image from his seal.