These are characters not taken. if there's a line through it, it's taken, I'll try to update it every week.
Royal Family:
Schneizel el Britannia
Cornellia li Britannia
Holy Brittanian Empire:
Cécile Croomy
Lloyd Asplund
Gilbert G.P. Guilford
Villetta Nu
Jeremiah Gottwald
Knights of the Round:
3:Gino Weinberg
6:Anya Alstreim
7:Suzaku Kururugi
Black Knights:
Zero/Lelouch Lamperouge
C.C.
Kallen Kozuki
Li Xingke
Kaname Ohgi
Kyoshiro Tohdoh
Zhou Xianglin
Diethard Reid
Rakshata Chawla
Asahina Shogo
Hong Gu
Indira Tharoor
Chiba Nagisa
Ahmad Khayrallah
Nguyen Van Nguu
Frederik Szymanowski
Minami Yonutsaka
Sugiyama Kento
Tamaki Shinichiro
Yusk
Sonthi Khun-moo uki
Ashford Academy:
Milly Ashford
Rivalz Cardemonde
Nina Einstein
Sayoko Shinozaki