Bismarck Waldstein

Bismarck Waldstein (ビスマルク・ヴァルトシュタイン, Bisumaruku Varutoshutain) is a man who bears the title of the Knight of One under Charles, the strongest amongst the Knights of the Round. He pilots the Knightmare Frame Galahad, and keeps his left eye sewn shut. Despite his status and combat abilities, he believes that war should be used as a last resort, and also sees strength without restraint as needless violence. He was previously the Knight of Five.

During the second battle of Tokyo, Bismarck leads the Britannian forces guarding the shore against Li Xingke's invasion force. Li and Bismarck battle, with Li unable to defeat him. Bismarck compliments Li's skill when he purposefully takes a hit to move into position to rescue the Chinese command vessel. During Schneizel's attempted coup d'état of Emperor Charles, he intervenes to stop Suzaku's assassination attempt on the Emperor. Suzaku's "live" command urges him to flee before they even begin fighting, indicating that Waldstein is extremely dangerous.

Following the death of the Emperor and Lelouch's ascension to the throne, Bismarck leads three of the remaining Knights of the Round and a squadron of Knightmares in an attempt to remove Lelouch from power. After Suzaku decimates all but Bismarck, Bismarck attempts to use his Geass, which allows him to see a few seconds into the future, to even the odds, claiming that the only person he ever used it against was Marianne. Suzaku's "live" command allows him to overcome Bismarck's Geass, and he slices the Galahad in half. Bismarck dies gasping Marianne's name.

Nightmare of Nunnally
He appears as the Knight of One, as a zombie member of the Knights of the Round in Nightmare of Nunnally. He and the other zombified Rounds face off in Sutherland Sieg-like machines against the contingent of forces led by Zero, Suzaku, and Euphemia li Britannia, and personally fights Zero. Upon Charles and Marianne's defeat inside Eden Vital, he concedes defeat with their passing as well, and crumbles into dust along with the rest of the Rounds.