AT-AT

All Terrain Armored Transport (AT-AT)
Production information
Manufacturer	Imperial Robotic Factories
Product line	All Terrain series
Model	All Terrain Armored Transport
Class	Assault walker
Technical specifications
Length	20 meters
Height/depth	22.5 meters
Maximum speed	60 km/h
Armament	Heavy laser cannons (2) Medium repeating blasters (2) Durasteel footpads (4)
Complement	74-Z Speeder Bikes AT-STs (2) Heavy weaponry
Crew	Pilot (1) Gunner/co-pilot (1) Commander (1)
Passengers	40 Stormtroopers 40 Storm Commandos
Usage
Role(s)	Armor Mechanized infantry Self-propelled artillery Troop transport Walker
Era(s)	The Last of the Droids
Affiliation	Galactic Empire

[Source]

The All Terrain Armored Transport (AT-AT) is a Imperial walker used by the Galactic Empire during The Last of the Droids era. AT-ATs were designed for armor, so B1 Battle Droids, Armored Assault Tanks, or even Hailfire Droids couldn't destroy them. That meant the New Confederacy of Independent Systems had to call in a Droid Gunship to defeat these.