In espionage, agents under non-official cover (NOC) are operatives who assume covert roles in organizations without official ties to the government for which they work. Such agents or operatives are typically abbreviated in espionage lingo as a NOC (pronounced “knock”). These agents are also known as “illegals”. Non-official cover is contrasted with official cover, where an agent assumes a position at an otherwise benign department of their government, such as the diplomatic service. This provides the agent with official diplomatic immunity, thus protecting them from the steep punishments normally meted out to captured spies. Upon discovery of an official cover agent’s secret hostile role, the host nation often declares the agent persona non grata and orders them to leave the country.

Agents under non-official cover do not have this “safety net”, and if captured or charged they are subject to severe criminal punishments, up to and including execution. Agents under non-official cover are also usually trained to deny any connection with their government, thus preserving plausible deniability, but also denying them any hope of diplomatic legal assistance or official acknowledgment of their service. Sometimes, entire front companies or strawman entities are established in order to provide false identities for agents.