The blind Norse god who accidentally killed Baldr was Höðr, also commonly anglicized as Hod or Hoder.
Baldr, son of Odin and Frigg, was beloved by the gods and believed invulnerable after Frigg obtained oaths from nearly every thing in the world. She overlooked mistletoe because it seemed too young and harmless. The gods then amused themselves by throwing objects at Baldr, confident that none could injure him.
Loki discovered the omission and made a weapon from mistletoe. In Snorri’s account, Loki guided Höðr’s hand as the blind god joined the game, causing the mistletoe missile to strike and kill Baldr. Höðr’s blindness and Loki’s manipulation make the killing accidental in the usual retelling, although the surviving sources vary in detail. After Baldr’s death, Váli—another son of Odin—avenges him by killing Höðr. Do not confuse Höðr with Vidarr, who avenges Odin at Ragnarök, or Hermóðr, who journeys to Hel seeking Baldr’s release.