Marianne vi Britannia is Lelouch vi Britannia's mother and Empress of the Holy Britannian Empire in the anime series Code Geass. Her son remembered her as a loving and caring mother, who died years ago, but in reality she survived and together with Charles zi Britannia she planned the creation of C's world, disregarding the possible deaths of her own children. Due to her role in the plan, she appears as the secondary antagonist.
She was voiced by Asako Dodo in Japanese and Kari Wahlgren in English.
Marianne vi Britannia is the late 98th Empress of the Holy Britannian Empire and the mother of Lelouch and Nunnally. Her commoner status by birth caused her to earn the jealousy of other imperial wives and nobles, which Lelouch suspected had resulted in her murder. Lelouch's investigation revealed, however, that several members of the Imperial House not related to her by blood respected and admired Empress Marianne, such as Clovis, Euphemia, especially Cornelia, who idolized her and put a lot of fruitless effort into investigating the assassination. Even some Britannians outside the Imperial Family, such as Jeremiah Gottwald, respected and admired Marianne.
It is hinted that her supporters were the Ashford Foundation, which explains why their social statuses were ruined after her death and why they consented to protect Lelouch and Nunnally. She had also piloted one of the earliest Knightmare Frames, the Ganymede, which was developed by the Ashford family and is well known for her superior Knightmare Frame piloting skills, hence the nickname, "Marianne the Flash". She also became a member of the Knights of the Round thanks to these skills. Several times throughout the series, Marianne's consciousness has been shown to be communicating with C.C. as a side effect of her Geass.
In other media
The light novels reveal that Marianne was driven to greater insanity by her Geass than even Charles had been. She experimented on many people using her Geass, including her own children. After the great success she experienced while testing on Lelouch and Nunnaly, she considered wedding the two to create a child who would be the perfect container of the Code.
Nunnally in Wonderland
In Code Geass: Nunnally in Wonderland, Marianne plays the role of the Queen of Hearts. When the King of Hearts (Charles zi Britannia) refuses to let Nunnally go through the castle to get to the path that will allow her to leave Wonderland, the Queen of Hearts appears along with the Knave of Hearts (V.V.). She agrees to let Nunnally go through the castle, but on one condition: Nunnally must play a game of croquet with her. In addition, if Nunnally loses, she will lose her head. However, this is interrupted by the arrival of the White King and Queen (Cornelia li Britannia and Euphemia li Britannia respectively) and the Red King and Queen (Schneizel el Britannia and Kanon Maldini respectively), with both the White Queen and the Red King expressing their different views on croquet. While this is happening, Nunnally manages to slip away and continues towards the exit.