Chara, also known as the fallen human, is the first human to fall into the Underground.  She is distinct from the eighth fallen human, Frisk. Her primary role is in the backstory of the Dreemurr family, though she also appears at the end of the Genocide Route to erase the world. Both of these make her a major character in Undertale.  Chara has dawned a genocidal and crazed personality, not afraid to harm anyone she comes across, all in an attempt to erase the world, and move on to the next.