Probe: the Protoss Worker Drone of StarCraft

The probe is the basic protoss worker, a small robotic drone that gathers resources and builds protoss bases. It doesn't build anything by hand. Instead it plants beacons that let whole structures warp in from far away, which is why a few probes can raise a working base on a new world very quickly. The Khalai designed probes for colonies on worlds too dangerous for living workers, and every protoss faction still uses them. (StarCraft (manual); StarCraft Compendium: Probe; Probe (StarCraft II official site))

What does a probe do?#

A probe has two jobs: feeding the protoss war machine and building its bases. It harvests the minerals and vespene gas that protoss industry runs on, bringing them back to the nexus. It also makes and plants warp beacons that let fully working buildings be teleported in, originally all the way from Aiur. That lets the protoss settle new planets, or set up a staging point near an enemy, with only a few probes on the ground. (StarCraft (manual); StarCraft Compendium: Probe)

Probes also go out ahead of armies. Blizzard's StarCraft II unit page describes them as rough and ready spies, sent to scout possible enemy camps before the warriors follow. (Probe (StarCraft II official site))

Brood War shows the job in action. When Kerrigan located the Uraj crystal on Braxis, the protoss broke through the Dominion defences and sent in a probe to carry it out. (StarCraft: Brood War)

How is a probe built?#

It's built light and cheap. The probe's outer shell gives little protection, even with its plasma shield, but the low weight lets it work almost anywhere without losing speed. The frame absorbs light and turns it into energy, so it doesn't need a separate power supply. Probes are described as self-sufficient, easy to produce and simple to run. (Probe (StarCraft II official site); StarCraft II: Legacy of the Void)

Because they were made for hostile worlds full of dangerous wildlife, probes carry a miniature energy projector that fires a particle beam. Normally the beam cuts mineral crystals and collects samples, but it can be boosted to do real damage to anything that threatens the probe. (StarCraft (manual); Probe (StarCraft II official site))

Alternity: StarCraft Edition, the licensed tabletop roleplaying game from Wizards of the Coast, adds a few details of its own: probes are run by artificial intelligence, can build facilities from scratch, can be pressed into service as a last line of defence, and are such a common sight that hundreds of them work the streets of a protoss settlement. (Alternity: StarCraft Edition)

Ordinary probes aren't programmed with personality traits like bravery or curiosity, which is why Blizzard's spotlight video for Probius, the probe hero of the non-canon crossover Heroes of the Storm, treats him as the odd one out. (Probius Spotlight, Heroes of the Storm)

Where do probes come from?#

The Khalai caste designed the first probes to lay the foundations of protoss colonies on hostile worlds, where sending living workers would cost too many lives. (StarCraft Compendium: Probe)

The design goes back to the protoss Second Age. Probes of that era, built in the style of the robotics of the time, had an elegant, almost luxurious look. Probes of the Great War period had longer stabiliser fins, but phase-smiths learned that the fins could become a liability in the middle of a large, vicious battle. A few probes that have been running since the Second Age were still in service after 2506. (StarCraft II: Legacy of the Void)

How do protoss factions use probes differently?#

Each faction tunes the probe to its own taste. These variants come from the descriptions of the probe skins in the StarCraft II Collections tab. (StarCraft II: Legacy of the Void)

• Daelaam: Daelaam probes are set to gather resources with as little harm to the local environment as possible. (StarCraft II: Legacy of the Void)
• Purifiers: Purifier probes are linked into the Purifiers' data web, which makes them models of efficiency. (StarCraft II: Legacy of the Void)
• Tal'darim: The Tal'darim don't bother with the Daelaam's environmental care. (StarCraft II: Legacy of the Void)
• Ihan-rii: Probes of the ancient Ihan-rii could fold into perfect cubes for storage during long deep space hibernation. (StarCraft II: Legacy of the Void)

Heroes of the Storm, a non-canon crossover, adds a joke of its own: the Dominion Engineering Corps keeps trying to copy probe technology, much to the annoyance of the union that represents SCV pilots. (Heroes of the Storm)

Probius and the Reclamation of Aiur#

The one probe with a name and a story is Probius. In the opening cinematic of Legacy of the Void, the zealot Kaldalis and his squad defend a probe while it warps in a pylon during the first landing on Aiur. The squad takes heavy losses, but the pylon goes up and reinforcements warp in, giving the Golden Armada its beachhead for the Reclamation of Aiur. Blizzard later named that probe Probius when it made him a hero in Heroes of the Storm. (StarCraft II: Legacy of the Void; Probius: Curious Probe)

More on the probe's place in the protoss army is on the protoss units overview. (StarCraft (manual); StarCraft II: Legacy of the Void)