Military - Drone incursions around military bases can interfere with flight operations. Cameras located on the drone itself can also present a compromise to security.
Prisons - Correctional facilities have been compromised by drones flying in illegal contraband including drugs, weapons, and cellphones.
Critical Infrastructure - Nuclear facilities, utilities, communications hubs, and other infrastructure can be vulnerable to drone infiltrations.
Airports - Drones intruding into airport facilities pose a potentially deadly hazard to airplane flights. Well publicized events have occurred where airports have been shut down due to drone activity in the vicinity.
VIP Protection - Various summits (such as world leader conferences, NATO, etc.) can be vulnerable to drones carrying explosive devices.
Privacy - Drones have been used to conduct video surveillance of dignitaries and celebrities.
Public Events - Sporting events, marathon races, concerts, and other public events are vulnerable to drone activity used for nefarious purposes. Additionally, video captures of events such as sports stadium events can be illegally taken and transmitted in real-time.
Corporate Espionage -- Drones can fly close to corporate facilities. Equipped with the requisite listening devices, drones can then capture transmissions and decipher their content.