Most guards are classified roughly according to their relative danger to the player. The game difficulty setting and mission difficulty level determine the number of guards of each class present at the start of a mission; each corporation's guards within each class are equally likely to appear.^[1]

	FTM	K&O	Plastech	Sankaku
Common	Security Guard	Security Guard	Security Guard	Security Guard Obake Drone v1.0
Common Drone	Camera Drone Pulse Drone
Elite	Barrier Guard Elite Security Support Guard	Elite Security Flack Guard Heavy Security Spec Ops Support Guard	Elite Security Modded MkI Siren 1.0	Akuma Drone Elite Security Null Drone Obake Drone v2.0
Lvl 2 Elite	Elite Barrier Guard	Elite Heavy Security Elite Spec Ops	Modded MkII Siren 2.0	Akuma 2.0 Null Drone 2.0
OMNI	OMNI Harbinger OMNI Protector OMNI Soldier

Found in the Contingency Plan DLC.

Some enemy units are not classified because they appear depending on the mission type, regardless of the mission difficulty level:

• Captains appear in Detention Centers, some Security Dispatches and some Vaults.
• Financial Executives appear in Chief Financial Suites.
• Refit Drones appear in Drone Rescue side-missions.
• Scientists appear in Program Compile side-missions, and in the OMNI Foundry Lab mission.

Additionally, Enforcers and Elite Enforcers are not classified, because they are never present at the start of the mission.