The Essex County Hospital Center, also known as the Overbrook Hospital, the Overbrook Asylum, or simply the Overbrook, was a psychiatric hospital that was located around 125 Fairview Avenue in the Township of Cedar Grove, New Jersey. It was used as a general hospital then converted to house patients with mental disorders. The original hospital was located at the edge of the Hilltop Reservation and designated a Conservation Easement in 2001 by the New Jersey Department of Environmental Protection; the site now is part of the Essex County park system. A new hospital opened in 2006, and the site of the original hospital was converted to a park and townhomes in 2017.

In 1896, a large portion of land was purchased by the City of Newark, New Jersey; the land was bought to build a new hospital to relieve pressure in the overcrowded Newark Hospital. During the late 1800s and early 1900s, many buildings were built that housed patients and other facilities, such as a power house, laundromat, and theater. According to Weird New Jersey, in the winter of 1917, the hospital suffered a catastrophe with the failure of the hospital's boilers and 24 patients freezing to death in their beds. In the mid-1920s, the tri-state mental correction board bought the land and converted Overbrook into a mental institution. The Overbrook asylum ran on, adding several add-ons and new wards until its closure in the winter of 2007.

In late 2006, the new Essex County Hospital Center 40°51′07″N 74°14′03″W / 40.851985°N 74.234172°W / 40.851985; -74.234172 opened just down the road from the site of the original Overbrook Hospital. This center houses chronically ill psychiatric patients in need of longer lengths of stay than are available in community hospitals and medical centers. The new center takes a cutting edge approach to behavioral health care and its layout and programs stand in stark contrast to the hundred-year-old facility it replaced. It is located at 204 Grove Avenue in Cedar Grove.

After years of back and forth about what the old hospitals in Cedar Grove were to become, county spokesman Anthony Puglisi stated that the property of these hospitals will become a park. This statement was made in 2015 and the project was completed in 2017. The vast 77 acres purchased by the county now is partially a park. This is now the 23rd space to be added to the Essex County park system. The remaining space was turned into townhomes and condominiums.

• Henry Alexander Davidson from 1957 to 1969.

• Weird NJ History, Photos, Legends of Essex County Hospital (AKA Overbrook Asylum for the Insane).
• Antiquity Echoes History, present day photos, and video of the Essex County Hospital Center grounds.
• Shadows and Rust Recent photographs of the inside and outside of the site prior to demolition.
• North Jersey Exploration Pictures of Overbrook Hospital.
• Vacant New Jersey Photographs of Essex County Hospital Center.
• White Enamel Interactive imagery and film using the Essex County Hospital Center.