Barnham Cross Common is a 69.1-hectare (171-acre) biological Site of Special Scientific Interest on the southern outskirts of Thetford in Norfolk, England.

[1][2] It is owned by Thetford Town Council and is registered common land.

[8] This grassland and heath common has diverse habitats and a rich flora, including several nationally rare plants.

There are nearly a hundred species of birds, including sixty which breed on the site, and a wide range of invertebrates.

Part of the land designated as Barnham Cross Common SSSI is owned by the Ministry of Defence.