Doctor Jonas Ravencroft, a descendant of British settler Molly Ravencroft, purchased the land in Westchester County in 1899, determined to provide proper psychiatric care for the people of New York. Despite numerous setbacks, by the early 1900s he had established the Ravencroft Institute for the Criminally Insane. At some point, Doctor Ravencroft took to recording a journal detailing the history of Westchester County, his family, and the Ravencroft Institute.
While a brilliant psychologist by the standards of his time, Doctor Ravencroft naively placed his trust in Doctor Nathaniel Essex - a sadistic mad scientist who proceeded to build a secret laboratory under the Ravencroft Institute, where he carried out numerous unethical experiments. After the disappearance of Doctor Claudia Russell, Doctor Ravencroft suspected Essex to be responsible and eventually ended his reign of terror over the institute.
Despite his initial skepticism, Doctor Ravencroft eventually became a believer in the supernatural after personally encountering mystical beings such as Loki Laufeyson. In the 1930s, Weapon Plus commandeered Ravencroft Institute and began performing cruel experiments on the inmates with the aid of Count Dracula, with Doctor Ravencroft being - in his own words - too much of a coward to stop them. When Captain America and Bucky Barnes attacked the institute looking to rescue a friend who'd been abducted, Doctor Ravencroft unleashed the monstrous results of Weapon Plus' experiments before committing suicide.
- Journal of Jonas Ravencroft: During his life, Ravencroft kept a journal documenting the history of the facility and the land upon which it was built. After his death his journal was buried in the foundations of the Institute and unearthed following its destruction, coming into the possession of Misty Knight.
- 2 appearance(s) of Jonas Ravencroft (Earth-616)
- 2 minor appearance(s) of Jonas Ravencroft (Earth-616)
- 3 mention(s) of Jonas Ravencroft (Earth-616)
- 1 image(s) of Jonas Ravencroft (Earth-616)
- 1 quotation(s) by or about Jonas Ravencroft (Earth-616)
- 1 item(s) used/owned by Jonas Ravencroft (Earth-616)