Sith stalker armor, painfully grafted onto the wearer's flesh and bone, was meant to transform dark side disciples into powerful Sith assassins. It had an intimidating appearance that was designed to inspire fear in any enemy.
Rather than utilize gauntlets, stalker armor instead replaced the vast majority of the hands with prostheses, though some flesh remained, allowing the user to apply Force lightning in combat without fear of it backfiring. The prostheses featured a set of metal claws attached to the finger tips. Despite their considerable length, they did not appear to cause any inconvenience on the part of the wearer, though this was likely just a result of practiced use. The head protection consisted of a form-fitting helmet that covered the entire head. The helmet face-plate resembled a Ubese bounty hunter mask with a Mandalorian-style T-bar visor. The armor also appeared to include some type of breathing apparatus, though the mechanism appeared to be controlled by the wearer, rather than automated, as the breathing pattern was forced and erratic.
Protecting the neck was a high metal collar that connected to a form-fitting pauldron protecting the right shoulder. The right forearm was protected by a set angular metal plates grafted to the flesh and connecting to the largely prosthetic right hand. The left arm and shoulder were left bare. The chest was protected by a set of ribbed, flexible armor plates. The armor included a series of leather belts, used to hold lightsabers taken from defeated opponents.
Below the belts were another series of ribbed plates forming a girdle that protected the waist and crotch. Whatever leg protection was utilized remains hidden by the ragged, floor-length combat skirt. Beneath the plates and combat skirt, the wearer was clad in a skin-tight black bodysuit made of what appeared to be leather. This suit was also specially made to avoid hindering the wearers physical abilities of strength and agility, nor their skill with the Force.
During his mission to Kashyyyk during the Great Jedi Purge, Darth Vader's secret apprentice, Galen Marek, codenamed Starkiller, wore the Sith Stalker Armor while experiencing a Force vision in which he killed a Jedi Knight. He later saw the same armor again while fighting a vision of himself wearing it in the Jedi Temple on Coruscant.
In the dark side ending of Star Wars: The Force Unleashed, Galen Marek was grievously wounded by Emperor Palpatine but was salvaged with his body reconstructed similar to how Darth Vader was when he became the Emperor's Sith apprentice.
There are six lightsabers on Marek's belt in this costume: his new Sith lightsaber, which features a set of three spiked blade guards; his original lightsaber that he built under Vader's tutelage; Rahm Kota's lightsaber, which also served as Marek's second; one half of the lightsaber that previously belonged to Darth Maul; Darth Vader's lightsaber; and the top portion of Kazdan Paratus' dual bladed lightsaber staff (dual blades are only in the Wii and DS versions).
Once completing the game and choosing the dark side ending, players have the option of playing again and wearing the Sith Stalker Armor. Modified versions of it are featured in the Ultimate Sith Edition version of the game. During the Tatooine mission, the player wears a set dubbed the "Desert Survival Gear", which includes Tusken Raider garb worn over the armor itself. In the Hoth mission, a variant referred to as the "Dark Lord's Armor" is featured. The description stub stated that it was largely inspired by Vader's armor, and it included many modifications from the standard Sith Stalker Armor. The original skin-tight leather bodysuit and the ribbed abdominal plates are replaced by a full body-suit made of the same quilted material as the one featured on Vader's armor, along with similar looking pectoral armor. The hands are gloved and the helmet has an outwards slanting metal plate attached that protects the rear and sides of the neck, and mimics the silhouette of Vader's helmet.
- Star Wars: The Force Unleashed: Ultimate Sith Edition