Ashtead Common (c. 200 ha)  is a wooded area to the north of the village of Ashtead in England which is open to the public. It is owned and managed by the City of London Corporation. 180.5 ha of the common are a National Nature Reserve. Together with Epsom Common it forms part of a larger area of open countryside called Epsom and Ashtead Commons which is designated a Site of Special Scientific Interest.
Ashtead Common has been part of the Epsom and Ashtead Commons Site of Special Scientific Interest since 1955 because of its community of breeding birds. It has also been a National Nature Reserve since 1995 because of the wood of decaying ancient trees and the rare invertebrates that live in it. It contains a wooded common with over 2300 pollarded oaks which are between 300 and 400 years old. These provide a habitat for many rare and endangered deadwood species. The area is of conservation interest in Britain and Europe. Also within the common are bracken, scrub grassland, semi-improved neutral grassland and various aquatic habitats.
When the railway companies wanted to build a new line to connect Chessington South railway station with Leatherhead railway station in the 1930s, they were denied planning permission because of the importance of the area.
Ashtead Common, together with Epsom Common, extends from the M25 Junction 9 near Leatherhead to the outskirts of Epsom. There are many entrances to the common for walkers, including in north Ashtead and Epsom.
- R. Warnock, Superintendent of Ashtead Common, P. Ritchie, Senior Keeper (2005). "ASHTEAD COMMON NATIONAL NATURE RESERVE Site Management Plan 1st April 2005 – 31st March 2010" (PDF). Site Management Plan. Corporation of London Open Spaces Dapartment. Retrieved 25 March 2010.
- "Epsom And Ashtead Commons citation" (PDF). Sites of Special Scientific Interest. Natural England.
- "Map of Epsom And Ashtead Commons". Sites of Special Scientific Interest. Natural England.
- English Nature[dead link]
- Conservation evidence
- Leatherhead local history
- "Thames Down Link" (PDF). Surrey County Council. Retrieved 6 January 2011.