While Dr. Jekyll is the character we see initially, and he's the one who creates the potion that transforms him, Hyde is the embodiment of the darker, more sinister side of Jekyll's personality. He's depicted as physically repulsive, cruel, and violent, representing the unchecked evil that lurks within all of us.
It's important to note: While Hyde is the villain in the traditional sense, the story explores the complex nature of good and evil within a single person. Jekyll, in his desire to separate his good and bad aspects, ultimately releases a destructive force that he can no longer control.