Shadow All Terrain Armored Transport

"What the hell is that?!?"

- Rebel Army soldier

The Shadow All Terrain Armored Transport, or Shadow AT-AT was a variant of the walker. It had stealth capabilities, but the main intent was to strike fear into enemies and intimidate populations. Originally designed by Lord Shadowspawn for use by Gamma Force, his personal Imperial unit, the Shadow AT-AT proved to be very effective and was manufactured by Kuat Drive Yards for more extensive use.

Details
The Shadow AT-AT used the standard AT-AT walker design, but was made out of pure black durasteel. Though it did have stealth capabilities, the main goal was to intimidate and frighten enemies. Rebel Alliance soldiers noted it was one of the most horrifying things they faced in battle. It had a cloaking generator, enabling it to become invisible. It carried a squadron of forty shadow stormtroopers. They were piloted by hand picked Imperial Army Pilots.

Often these walkers would work with regular AT-ATs as back up, appearing out of nowhere using their cloaking generators when they were right in front the enemy. Similar tactics were also used and had a very demoralizing effect on troops who had to face the behemoths.

Production
"We need a vehicle that can strike fear in our opponents, paralyzing them and distracting them while we kill them."

- Lord Shadowspawn

The idea was originally thought up of by Lord Shadowspawn, an Imperial Inquisitor and an Imperial Intelligence agent. He used fear a lot against his enemies, and was looking for a command vehicle to use that would be fearsome to his enemies. Seeing officer using a modified  on Kashyyyk, and General Aurelius Tempest use the advanced AT-AT Tempest One, he came up with the Shadow AT-AT. Using credits given to him by Emperor Palpatine, Shadowspawn had Kuat Drive Yards manufacture three of them at first, then later ten.

Usage
He used it on numerous planets during the Galactic Civil War. Soldiers of the Alliance to Restore the Republic admitted it was one of the scariest things they faced on the battlefield. Following Palpatine's and Darth Vader's deaths over Endor, Shadowspawn used the Shadow AT-ATs extensively during his campaign to unite the Imperial warlords and reestablished the Galactic Empire. His new empire became known as the Shadow Empire. They were often seen supporting All Terrain Ion Cannons.

Obsolescence
"That can't be an AT-AT . . . that must be some sorta ghost walker!"

- Anonymous Darth Krayt loyalist

They vehicle was still in use by 137 ABY. Both Darth Krayt's Galactic Empire and the Fel Empire used the Shadow AT-AT. Shadowspawn, who was still alive at the time due to placing himself in stasis years earlier, encouraged it's usage and supported Emperor Fel, and thus the Fel loyalist Imperial Army elements used it frequently along side All Terrain Ion Cannons.

Behind the scenes
The author created this after reading the article for it on Wookieepedia. He thought it was an awesome concept, but was disappointed to see that it was never used in the canon Star Wars universe (theoretically it was, but not in any books or comics). He ended up deciding it was perfect to be used by his character, Lord Shadowspawn, who relied on fear a lot, which is the primary purpose of the vehicle in the canon universe.