Height: 174 cm

Euphemia li Britannia is Lelouch's half-sister and the Third Princess of the Britannian Imperial Family; she is the sibling Lelouch cares most about after Nunnally. She is a kindhearted and open-minded woman who despises conflict in any form.

Euphemia joins her older sister Cornelia in governing Area 11, becoming the Sub-Vicereine. She develops a relationship with Suzaku Kururugi, whose views reflect her own, and eventually appoints him as her personal Knight.