In one aspect, a handheld lighting system is disclosed, which comprises a handheld housing extending from a proximal end to a distal end, and a light module disposed at least partially in the housing. The handheld lighting system further includes a removable and replaceable power module that is coupled to the housing (e.g., it is at least partially disposed within the housing) and is electrically coupled to the light module, e.g., through a pair of electrical leads, for providing electrical power thereto. Light intensity from the light module may be controlled from a knob on the power module. Various adapters can allow the lighting system to attach to a multitude of medical, industrial, dental or veterinary endoscopes or other instruments.