*Euphemia li Britannia was the third princess of the Britannian Imperial Family. Euphemia is Lelouch vi Britannia's half-sister and the sister he cared most about after Nunnally. Euphemia was the Sub-Viceroy of Area 11, a role she admittedly did not enjoy. Euphemia admired her older sister, Cornelia, but despised all combat in general, though was capable of piloting a Knightmare Frame and using a firearm.

Euphemia is said to be very beautiful with pink hair that reached below her waist. It is usually styled downwards with two buns on each side of her head while she has curly bangs hanging on the right side of her face, bluish-violet eyes and she is taller than average height being slightly shorter than Lelouch vi Britannia and Suzaku Kururugi.

She is usually seen wearing a lilac and white dress with a rose choker.

Although Euphemia is a member of the Britannian royal family, she remains pure-hearted and open-minded to everyone around her and treats everyone with respect even if they are not Britannian; this universal respect probably stems from her own childhood experiences with her siblings Lelouch vi Britannia and Nunnally vi Britannia whose mother wasn't from the nobility and thus were looked upon with disdain by the other members of the Britannian Imperial Family. She is the second person in the Imperial Family to discover that Lelouch is alive and first to know his alter ego as Zero, having deduced it after the hotel hijacking incident. In her childhood, she was quite close to Lelouch and Nunnally. She develops a close bond with Suzaku Kururugi due to their shared belief that a problem must be changed from within.*