Cornelia li Britannia (コーネリア・リ・ブリタニア Kōneria ri Buritania), 27 years old (28 at R2), is the second princess of the Britannian Imperial Family and is Lelouch's half-sister. She is extremely skilled in Knightmare Frame combat and completed the establishment of Area 18 shortly before arriving in Area 11. She was one of the main antagonists during the first season, but from the second season onwards she became a neutral character.

She is voiced by Junko Minagawa (Japanese), and Mary Elizabeth McGlynn (English).