Clarke Griffin
(Eliza Taylor)

Clarke, the de facto leader of Skaikru, saved everyone (again) at the end of Season 3 by entering the City of Light. Under Lexa’s (Alycia Debnam-Carey) protection and using Raven’s (Lindsey Morgan) hacker prowess, she flipped A.L.I.E’s kill switch to keep everyone from being engulfed by the City of Light.

The only problem is that before she “died,” A.L.I.E. told Clarke that the world’s nuclear power stations are melting down and soon the world will be uninhabitable due to the radiation levels, which means Clarke has about six months to figure out how to save her people (again).