Sentry-bots, also referred to as sentrybots, are enemies in Ratchet & Clank. They were blargian robots manufactured by Drek Industries in the same robot factory on planet Quartu that produced Clank.
Sentry-bots are replaced by warbots in the 2016 re-imagined game and movie. Warbots have a largely different design, though they have a similar role in narrative, as the original series Clank was intended to be created as when produced in the factory on Quartu, and as the guards on board the Deplanetizer that the Hologuise is used to sneak past.
Sentry-bots were created in a factory by Clank's mother. At the beginning of the game, the factory instead produced Clank, a defect. After Clank viewed an infobot revealing Chairman Drek's plan to extract a portion of Novalis, he fled the nearby sentry-bot.
Later, when first arriving on Quartu, Ratchet was unable to access the factory, due to the sentry-bots defending it. He used the Hologuise upon acquiring it to sneak past them in "Infiltrate the secure area", and again to get through Drek's fleet in "Find the coordinates for Drek's laser".
Sentry-bots have a similar design to Clank, having a metal look, with green eyes and antenna. However, they are much bulkier and more heavily armed. They have a green glowing light on their chest, and no mouth.
Sentry-bots will patrol a secure compound for intruders. They are slow and dumb when patrolling, and easily fooled by the Hologuise despite it only vaguely resembling a sentry-bot. When spotting an intruder, their lights will go from green to red, and they will either activate a nearby alarm or throw blasts of energy.
Many sentry-bots guard forcefields, and Ratchet must wave at them with the Hologuise on for them to be fooled and deactivated it. Aside from this, sentry-bots can be fought at will, but doing so will place a risk that they may activate an alarm. If active, a series of homing balls of energy will be deployed to continuously attack Ratchet until death or until fleeing the area, at which point all will reset.
Sentry-bots have good aim and fast bullet speed, but a slow rate of fire. They require a few hits to be destroyed. Useful weapons against them are the Glove of Doom, the Bomb Glove, and in close range, the Walloper. However, it is important to judge when to engage with the sentry-bots; they are best attacked when none of them are close to an alarm to activate, or when they are alone and can easily be caught off-guard.