A probe droid, also known as a recon droid or probot, was a type of droid that could be used for deep space exploration and reconnaissance, they are tenacious hunters and searchers. Notable models included the DRK-1 Dark Eye probe droid and the Viper probe droid. They could be equipped with both shields and blasters.
To locate the Rebel Alliance's secret base after they evacuated from Yavin 4, the Galactic Empire began Project Swarm, which saw probes sent out to find the hidden base. Eventually one such droid, a Viper model having arrived on the planet Hoth from its carrier, began to transmit a live feed of what appeared to be a power generator to the Empire, leading to an attack on Echo Base a short time later. The droid, however, was intercepted by Han Solo prior to the invasion, warning the Alliance and giving them some time to prepare.