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"Your Honor, I'd like to introduce holorecordings of the defendant at the moment of the massacre: IM4-821 from street level, IM4-822 from overhead, IM4-823 from down the block…"
―From the Denon murder trial of Dr. Cornelius Evazan[src]

The Mark IV sentry droid, also known as the IM4, was a small, multi-purpose sensor droid manufactured by the Imperial Department of Military Research and employed by the Galactic Empire.


Fitting their purpose, Mark IV droids were equipped with an extensive sensor complement in place of traditional weaponry. The droid featured electromagnetic, infrared, and visible-light sensors, in addition to three hours worth of holorecording memory. They were capable of flying up to 15 meters in the air via built-in repulsorlifts.

A Mark IV sentry droid

Because of their powerful sensory equipment, Mark IV droids were used for a variety of tasks: battlefield reconnaissance, surveying, and sentry and patrol duties. The droids were even capable of long-range surveillance due to the inclusion of a holorecording rig. Although equipped with basic personality programming and self-preservation instincts, Mark IV droids were compelled to obey orders given to them, leading cautious commanders to scout dangerous terrain ahead with the essentially expendable droids.


A Mark IV with stormtrooper

Hundreds of Mark IV droids were deployed from the Devastator during the Galactic Civil War to scout the planet of Tatooine, where they searched the crowded streets of Mos Eisley in cooperation with sandtroopers searching for C-3PO and R2-D2.

One such droid interrupted an ASP-series droid assembling what it thought to be an illegal antenna. The ASP droid responded by smashing the Mark IV.

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