In the world of the Matrix film trilogy, Sentinels are terrifying killing machines that continuously patrol the many sewers and caverns beneath the planet's ruined surface. They fly through the use of some form of electromagnetic levitation and are fast enough to intercept the hovercrafts used by the human resistance. Their bodies consist of a large pod-shaped head with several optic sensors, with many long metal tentacles extending from the back. This body structure has earned them the nickname "Squiddy" by the humans. Attached to the Sentinels' many tentacles are audio sensors that look like satellite dishes, which can pick up even the faintest sounds, making it necessary for Zion ships to shut down power when Sentinels are nearby. The Sentinels' tentacles may also end in sharp claws for ripping into ship hulls or impaling humans. The robots' "heads" are also outfitted with a laser for cutting into hovercraft hulls.
Frightening and deadly as they are, the Sentinels are not without vulnerabilities. They can be dispatched by lightning rifles carried by human fighters, APU or ship-mounted guns and rockets. They can also be shut down by EMP blasts, like all electrical devices.