Lord Voldemort
In the final battle, Voldemort's final Horcrux, a snake named Nagini, is killed. Voldemort tries to use the Elder Wand to kill Harry. However, due to Harry defeating Draco Malfoy (the current Elder Wand Master) earlier in the story, Harry is now the true Master of the Elder Wand. Because the Elder Wand will not kill Harry, Voldemort's killing curse actually hits himself. With no Horcruxes left, Voldemort dies.