Near the end of Frankenstein, when Victor dies aboard Robert Walton's ship, the monster becomes so stricken with grief that he vows to take his own life. Whether or not the monster stays true to his words and actually kills himself is unclear, but the events leading up to the final moments, the gravitas of the situation, the tone of the novel's ending, and the monster's promise all suggest that the monster does, in fact, die.

As the story progresses, Frankenstein's monster slowly begins to overcome his anger, aggressiveness, and immaturity; he comes to realize the mistakes he made in the past. He begins to change his behavior and attitude toward the world. Unlike the monster, Frankenstein doesn't change his ways: he is still selfish and adamant on destroying the very life that he created. This is exactly how he dies—relentlessly pursuing the creature that he abandoned and regretting that he didn't get the chance to kill him.

But when Victor dies in the novel's final moments, the monster believes that his life no longer has meaning or purpose. He feels immense remorse and sadness and loses all hope, both for himself and for the world which failed to accept him as an actual being, despite his kindness and desire for love and friendship. He vows to Walton,

I shall die, and what I now feel be no longer felt. Soon these burning miseries will be extinct. I shall ascend my funeral pile triumphantly and exult in the agony of the torturing flames. The light of that conflagration will fade away; my ashes will be swept into the sea by the winds. My spirit will sleep in peace, or if it thinks, it will not surely think thus. Farewell.

The monster then jumps out of a cabin window, lands on an iceberg, and floats away, never to be seen or heard from again.