A Zombie is a network-attached computer system that is secretly under the control of a remote malicious actor, though this control may not be evident for some time, or indeed at all.

Zombies are most commonly associated with botnets, large aggregates of computer systems on which malware has been installed for remote control purposes. Botnets are frequently used to launch distributed denial of service (DDoS) attacks, to send large quantities of bulk email, or to mine cryptocurrency for remote thieves in the background of regular activity.

The ability to detect zombie status and eliminate responsible malware components is a key claimed feature of many malware scanning programs.