Klaus Baudelaire is a fictional character in the popular children's book series, A Series of Unfortunate Events by Lemony Snicket. His first name is possibly derived from Claus von Bülow.

Klaus is the middle child of the Baudelaire orphans; he has an older sister named Violet and a younger sister named Sunny. He is twelve years old at the beginning of the series, and turns thirteen in The Vile Village. He is fourteen by the end of the series.