The present disclosure relates to semiconductor structures and, more particularly, to electrostatic discharge devices and methods of manufacture. The structure includes: a plurality of regions of a first dopant type; insulator material separating each region of the plurality of regions of the first dopant type; and a substrate contacting the plurality of regions of the first dopant type, the substrate comprising a base region of a second dopant type different than the first dopant type and an outer segment surrounding the plurality of regions of the first dopant type, the outer segment comprises an electrical resistivity higher than the second dopant type.