Mark Chambers

Mark Chambers was a human whose face appeared on a Node. The Node replied to Donna Noble's inquiry about the face, stating that "This flesh aspect was donated by Mark Chambers on the occasion of his death". This terrified Donna, who realised that the face on the node was a real face. (TV: Silence in the Library)

Behind the scenes
The role of the Mark Chambers node, known as "Node 2" in the closing credits of Silence in the Library, was credited to Joshua Dallas.