Death Troopers

The Death Troopers are a special type of black armored Stormtroopers that appear in the 2016 Star Wars movie, Rogue One. They serve as part of the Galactic Empire's Military Intelligence, and are most known to wield DLT-19 heavy blaster rifles. Their moniker was inspired by Emperor Palpatine's failed attempt to achieve immortality through use of a virus (Project Blackwing) that turned its victims into undead monsters. As Death Troopers were extremely skilled in combat and left few witnesses in their wake, this was an apt name. Death Troopers were the elite commandos of the Empire, and were trained in unarmed combat, sniping, and heavy weapons. They were also exceptionally good at covering their tracks, making them perfect for black-ops missions.

Rogue One
A legion of Death Troopers specifically act as bodyguards to Orson Krennic. The Death Troopers accompany Director Krennic when he visits Galen Erso to recruit him back to the team building the Death Star. When Erso refuses, Krennic orders the Death Troopers to enter the Erso house to search for Galen's family. Before they can reach the house, however, Erso's wife Lyra approaches and draws a gun. On Krennic's behalf, she is executed by the Death Troopers who also take Galen with them. Although they search for Galen's daughter Jyn, they cannot find her and are forced to leave the planet without her.

Years later, the Death Troopers are dispatched by Krennic to aid the Imperial Stormtroopers in the battle of Scarif. Theiy deployment turns the battle in favor of the Empire and the rebel forces attacking the Imperial base are annihilated. The Death Troopers who survive the battle are killed when Grand Moff Tarkin fires the Death Star at Scarif, destroying the base and everything around it.

Star Wars Rebels
The Death Troopers are set to appear in the third season of Star Wars Rebels.

Trivia

 * According to the Us Magazine Collector's Edition - Star Wars Rogue One article Going Rogue, the Death Troopers are comparable to the United States Navy SEALs.
 * Death Troopers is also the name of a Star Wars novel which came out in 2009 (now regarded as Star Wars Legends) under the title Star Wars: Death Troopers, written by author Joe Schreiber. In the plot, an Imperial prison barge named Purge breaks down in outer space while transporting 500 prisoners, including Han Solo and Chewbacca. Eventually, they come across a Star Destroyer drifting in the vast emptiness of space. At first, it appears that Star Destroyer is deserted and abandoned, but not for long. It is soon revealed that the abandoned vessel is overrun by zombies, which are the result of an experiment for a biological weapon, known only as Imperial bioweapons Project I71A, going horribly wrong. While the novel is now Legends material, some elements of the story have made their way into the official canon.
 * Their color and design of the Death Troopers may have been influenced by the Imperial Shadow Troopers.