Victor and his creature are psychological doubles in that Victor feels little remorse and has a great deal of difficulty taking responsibility for his actions, while his creature feels the full weight of his guilty conscience and takes more responsibility than, perhaps, he should. On his deathbed, Victor tells Captain Walton, "During these last days I have been occupied in examining my past conduct; nor do I find it blameable." His creature, on the other hand, says, "I am a wretch. I have murdered the lovely and the helpless; I have strangled the innocent as they slept, and grasped to death his throat who never injured me or any other living thing," and he asks his (dead) creator's pardon before he goes to take his own life.

Dr. Jekyll and Mr. Hyde are psychological doubles in that Dr. Jekyll is attempting to rid himself of any dark or malicious impulses that he has, and he ends up distilling all that evil impulse into another being who ultimately becomes more powerful than he. Essentially, Jekyll represents what is often good about humans, but he also fails to see the consequences of his actions (like Victor); Hyde represents our darker natures, and he also fails to consider consequences before he acts. Both lack foresight.

In Jekyll and Hyde, Hyde is pretty much pure evil, and no character in Frankenstein can be called that. Victor may make some serious errors in judgment, but his intentions are, in large part, good. He wanted to cure humanity of disease (just as Jekyll wants to cure us of our darker impulses which are not socially appropriate). The creature may kill a lot of people, but it is not purely out of malice; instead, he does it because he is hurt. He is not evil, just misunderstood and powerful. It is notable that both the creature and Hyde "outlive" their creators and are actually more powerful than the beings that made them.

Both novels deal with the scientists upsetting the laws of the universe. Both of the scientists are dabbling in the unknown, attempting to play God. In the case of Dr. Jekyll, he's trying to understand the dual nature of humans to be both good and evil, and he wants to separate the two. Dr. Frankenstein tries to balance his intellectual and social interactions.

Dr. Jekyll thinks if he can rid man of his evil side, man will be better off because "life would be rid of all that was unbearable; the unjust might go his way delivered from the aspirations and remorse of his more upright twin; and the just could walk steadfastly and securely on his upward path, . . . no longer exposed to disgrace and penitence by the hands of his extraneous evil." By separating the two, Jekyll would be separating the moral and the intellectual, and he felt man would be better off for it. Jekyll became too ambitious however.

Dr. Frankenstein's creation has also been referred to as his dark side, the embodiment of Frankenstein's evil self. Victor, like Jekyll, is science gone amok. He refuses to take responsibility for his creation, and innocent people are hurt, just as they are by Mr. Hyde. Both doctors don't understand human nature, and as a result, their results are disastrous. Both are also overambitious, allowing their experiments to control them. They lose sight of their goal, and in the end, they allow their evil sides to triumph.