St Mark's Church (dedicated in full to St Mark the Evangelist) is an Anglican church in the village of Hadlow Down in the district of Wealden, one of six local government districts in the English county of East Sussex. Founded in 1834 by a committed local resident who petitioned the Archbishop of Canterbury for permission to establish a chapel in the poor agricultural village, the church proved popular—despite the competing presence of two Nonconformist chapels nearby—and was extended in 1913. The stone-built church, with its tall spire and well-regarded "living churchyard" nature reserve, is now Hadlow Down's only remaining place of worship.