The Terror Walker was a massive droid attack walker developed by the Galactic Empire. It was designed to plow through large obstructions and annihilate anything in its path.
Prior to the Rebel Alliance's assault on Kamino in 1 BBY, Boba Fett was tasked with infiltrating the Rebel frigate Salvation. Acting under orders from Darth Vader, the bounty hunter was accompanied by a complement of specialized units, including terror troopers, specialized droids and the Terror Walker.
The Terror Walker was released onto the Salvation, and immediately began rampaging through the vessel, leveling all in its path. Its actions allowed companies of stormtroopers to access various areas of the ship and assist Boba Fett in his objective—capturing Juno Eclipse.
Fett was ultimately successful; however, the arrival of General Rahm Kota and the clone of Galen Marek coincided with his mission, and the Terror Walker engaged Marek's clone in single combat in the ship's Core.
Starkiller attacks the Terror Walker.
The Terror Walker fought against Marek's clone in the Salvations reactor core, a battlefield that would bring about its end. Using the reactor itself to deactivate the Walker's shield, Marek was able to damage the Terror Walker and commandeer it.
The Terror Walker was rammed into the core, and proceeded to self-destruct. Its useless body was later utilized by the clone to escape the volatile area. Whatever remained of the droid was obliterated when the Salvation impacted into Timira City.
This large droid was capable of exterminating almost anything in its way, thanks to its sharp claws. It was also armed with missiles and lasers to further increase its destructive capabilities. In this droid also comes the Terror Droids, smaller arachnid-type robots that attached themselves to unwilling victims.
The Terror Walker was introduced in Star Wars: The Force Unleashed II, and makes its first appearance in the final stages of the level "Aboard the Salvation"; the fight against the Terror Walker marks the end of the said chapter. Also, an entry on the Terror Walker's creation is included in the game's databank.
In the novel, the Terror Walker was destroyed when the clone hurled it into space while the Salvation was traveling through hyperspace. In the Wii version, the Terror Walker struggled to move, only to be sucked into the generating hyperdrive waves.