Dr. Jonas Harrow is a character that appears in the Marvel Comic Universe. He is a deranged and disgraced former surgeron who is most often an enemy of Spider-Man.
Over two decades ago, Harrow was disgraced as a surgeon and expelled from the medical profession for unorthodox experiments. Happening upon a near-dead criminal in the Bowery, Harrow, entertaining half-hearted hopes of redemption, cybernetically restored the criminal, who became the gangster Hammerhead. Harrow slid deeper into underworld research eventually seeking mind-controlling technology.
In recent years, Harrow enhanced criminals to superhuman status for a fee, the hapless Megawatt his first known subject. When Hammerhead rose to prominence, Harrow observed his ex-patient's battles with Spider-Man, whom he perceived as a challenge. He enhanced another criminal, the mutant Kangaroo (Frank Olver), who ungratefully scorned Harrow's schemes. Harrow continued providing services to villains like Living Laser, but when Will-O'-The-Wisp sought removal of his power, Harrow implanted a surgical device to extort him into theft.
When the Wisp rebelled while fighting the intervening Spider-Man, Harrow's device temporarily dissipated him. Using stolen information, Harrow developed a "variator ray" to control human emotion. By now obsessed with Spider-Man, he tested the device on the hero's self-appointed enemy, Daily Bugle publisher J. Jonah Jameson, whom he drove to a nervous breakdown. Gloating, Harrow widened the ray's range to the victims, only to have Spider-Man locate and destroy the ray. Undaunted, Harrow dared Spider-Man to confront him, but was defeated with one punch. Sentenced to Ryker's Island Prison, Harrow learned that inmate Armand DuBroth was blackmailing Warden Percy Rue into allowing DuBroth's use of the prison a base of criminal activities, including the release of select super-villains. Harrow and the Grey Gargoyle became the latest beneficiaries of DuBroth's scheme, but Spider-Man exposed the operation. Harrow went unheard of for years, although some incorrectly suspected him of being the Hobgoblin.