Edward Hyde, commonly known as simply Mr. Hyde, was the dark side of the good Dr. Henry Jekyll. Hyde was given form when Jekyll attempted to expell all evil from himself by means of a chemical formula using an unknown and "impure" saline ingredient. But instead of purging his evil Jekyll transformed into a younger version of himself more prone to depraved and immoral acts, who took the name Edward Hyde. Hyde committed many atrocities throughout London, including tramping on a little girl (he was collared by Richard Enfield and used Jekyll's bank account to cash a very large check to pay the girls family so they would not turn him in to the police) as well as brutally murdering Sir Danvers Carew.
Killing Sir Danvers brought the full wrath of Scotland Yard down upon Hyde, and he found himself doggedly pursued by Sir Danvers' lawyer Gabriel John Utterson (who was also Jekyll's lawyer), as well as Inspector Newcomen. To elude them, Hyde was forced to hide in Jekyll, and after the manhunt died down, Hyde began to emerge from Jekyll more and more often (often without the aide of the chemical), and seeing less and less of Jekyll around the house and more of Hyde made Jekyll's butler, Poole, suspect that Hyde had murdered the doctor.
By the time Hyde had completely taken Jekyll over, Poole and Utterson were (literally) breaking down Jekyll's office door, and to escape trial for the murder of Sir Danvers, Hyde swallowed poison and killed himself and Jekyll with him.
Dr. Jekyll and Mr. Hyde (1931)
Rather than an ordinary-looking albeit repugnant version of Jekyll, Edward Hyde is a brutal, hideous man physically resembling a Neanderthal. Hyde represents Jekyll's animal impulses, particularly his lust for prostitute Ivy Pearson. Upon his second release into the world, as a result of Jekyll's frustration over Muriel Carew's extended trip to Bath, Hyde goes immediately for the Variety Music Hall where Ivy works as a singer, and persuades her to accompany him, promising her that while he is "no gentleman," he is wealthy and can provide her a life of luxury if she will become his.
An emotionally and physically abusive relationship between the two follows. When he reads in the newspaper that Muriel and her father, General Carew, are returning to London, he hastily leaves. He then turns back into Jekyll, who, out of remorse (and without telling Ivy that he and Hyde are the same person) promises Ivy that Hyde will never bother her again.
However while walking in the park, Jekyll witnesses a cat kill a bird. This causes Jekyll to transform into Hyde for the first time without the use of the drug, and he went to Ivy's apartment and murdered her for daring to seek Jekyll's help. Afterward, Hyde, sought by the police, writing as Jekyll, enlisted Dr. Lanyon's help in acquiring the ingredients needed to recreate the formula so he could become Jekyll again and thus elude capture.
Afterward, Jekyll explained everything to Lanyon and promised never to take the drug again. However he turned into Hyde yet again and attempted to force himself on Muriel. General Carew and Hobson the butler rushed to the rescue and a fistfight between the three ensued, during which Hyde nearly killed Hobson by strangling him, before Carew pulled him off of the butler. Hyde then turned his attentions to the General whom he beat to death with his cane. Fleeing to Jekyll's laboratory, Hyde turned back into the doctor with the aid of the chemical.
Lanyon arrived with the police, and exposed Jekyll's secret. The attending police inspector did not believe a word of it...until Jekyll, nervous, turned into Hyde under duress. Overcoming their horror, the police attempted to apprehend Hyde who viciously fought them off. He grabbed a knife to defend himself, and a single shot fired from the inspector's gun ended Hyde's life. He transformed back into Jekyll in death.
League of Extraordinary Gentlemen
Jekyll and Hyde somehow survived, and fled to Paris to continue his depredations. Hyde was tracked down by Mina Murray and Allan Quatermain (with the help of C. Auguste Dupin, who drafted him into the turn-of-the-century incarnation of the League of Extraordinary Gentlemen. By this time, Hyde had mutated into a huge, hulking brute. Hyde later formed a kind of rapport with Mina, and ultimately died in battle with the invading Martians. London's Hyde Park was named for him following his sacrifice.