They are shown in collective groups of varying organizational sizes ranging from squads to legions and, for some, their armor and training is modified for special operations and environments.
With the falling of the Old Republic and the Rise of the Empire, the Clone Troopers were rechristened as Imperial Stormtroopers or were replaced by them. Without the guidance of their Jedi officers, Stormtroopers were "cut loose" to brutally enforce the new Imperial doctrine, to which they quickly built a reputation as merciless, uncompromising soldiers indoctrinated with unconditional loyalty to Emperor Palpatine. As the Empire went on, many races feared these troopers and were threatened to be arrested or killed on sight if anyone dared tried to mess with them or fight back. Alternatively, these troopers where noticeably less combat efficient than their counterparts from the Clone Wars, and relied more on weaponry and masses to achieve victory. They were also similarly disposable and expendable as the Clone Troopers.
The Stormtroopers are loyal and obedient, and they never question orders from high-ranking officials. They are also very merciless in battle.
Though many Stormtroopers are inaccurate at shooting their targets (mostly new recruits or inexperienced individuals), certain divisions, such as the Death Troopers and the Special Commando Advanced Recon (SCAR) troopers were exceedingly formidable; able to gun down almost any opponent in combat. Some, like Sergeant Kreel and his SCAR trooper squad (introduced in Marvel Comics' Star Wars series) were even capable of and specialized in using lightsabers, sniper rifles, melee weapons and martial arts, demolition equipment and heavy artillery. The most feared Stormtroopers however were the unit known as the 501st Legion, commonly sporting the moniker of "Vader's Fist". They served directly under Darth Vader himself, and often accompanied the Sith lord on his most important missions, including the Battle of Hoth.
The Stormtroopers made their debut appearance in the original Star Wars movie A New Hope, originally titled Star Wars back in 1977 until it was renamed in later releases.
A New Hope
The Stormtroopers were involved in search of the plans for the Death Star which were stolen by Rebel Spies, when it was assumed that the princess hidden them in a escape pod that crashed landed on the planet Tatooine, a group of troopers were sent down to search for them and soon realized they were also looking for two droids known as R2-D2 and C-3PO. The Stormtroopers tracked down the same Jawas that sold off the two droids and traced where they sold too, Lars Owen. They slaughtered both the Jawas and Lars and Beru after they were unable to find the droids but they would later spread their search to Mos Eisley where they found and attempted to stop Luke, Ben and the two droids from escaping aboard a ship known as the Millennium Falcon, piloted by Han Solo and Chewbacca.
When the Millenium Falcon was captured by the Death Star, Stormtroopers aboard the station were put on patrol and two of them were taken out by Luke and Han and stripped of their uniforms. When Luke, Han and Chewbacca made an attempt to rescue Princess Leia, the Stormtroopers ambushed them in Detention Block AA23, until they escaped down the garbage chute.
The Stormtroopers would soon catch up with Han, Luke, Leia and Chewbacca and attempted to capture or kill them. Han chased a few Stormtroopers down a corridor but soon ran away after he became face-to-face with millions of Stormtroopers. The Stormtroopers chasing Leia and Luke were trapped and unable to extend a bridge to get to the other side of the endless drop below them. However, they were able to jam the door behind them for a while and swing across to the other side. Their attempt to capture both the intruders would be in vain as they managed. The troopers who were stationed on the Death Star were later all killed along with the station's destruction.
The Empire Strikes Back
The Stormtroopers fought in the Battle of Hoth, and later accompanied Darth Vader in capturing the Rebels Han Leia and Chewbacca on Cloud City on Bespin. For unknown reasons, they tortured Han and later had him put in place for carbon freezing. After giving Han to the bounty hunter Boba Fett, the Stormtroopers escorted Leia and Chewbacca to Vader's ship but thanks to Lando Calrissian, they were captured, stripped of their weapons and sent to the security area quietly.
As everyone began to evacuate the Cloud City before more Imperials arrive, few Stormtroopers chased after Leia, Lando, Chewbacca, R2-D2, and C-3PO as they made their way back to the Millennium Falcon. Again their attempts to capture them were in vain as they were able to successfully escape.
Return of the Jedi
The Stormtroopers are first seen in this film when they flank Darth Vader's arrival on the Second Death Star, and later the Emperor himself. The Emperor had his best Troops stationed on the forest moon of Endor guarding the shield generator that was protecting the Second Death Star. As part of the Emperor's plan to rid of the Rebellion, he allowed a small group of Rebels to find the shield generator where a squadron of Stormtroopers ambushed them and were captured. However they were not expecting to face the Ewoks that inhabited the planet and engaged them in a battle throughout the forest. Even though the Troopers had the upper hand in weaponry, they were easily defeated and the Rebels succeeded in destroying the shield generator allowing Lando Calrissian and his fighter squadron to enter the Death Star and destroy it.
The Stormtroopers appear in Rogue One and will introduce three new kinds of Stormtroopers: Death Troopers, Hover Tank Troopers, and Shoretroopers. Here, even the normal variety of Stormtrooper are shown to be quite formidable fighters, as the Stormtroopers wipe out most of the Rebel forces during the Battle of Scarif.
The Stormtroopers appear in the Disney XD series, Star Wars Rebels. Set five years before the events of A New Hope, they fight against the growing Rebellion, led by Jedi-Cowboy Kanan Jarrus. In the series they are commonly nicknamed "Bucketheads" by the Rebels, because of their bucket-shaped helmets. Even in greater numbers, they always get outwitted and defeated by the elusive Rebels.
In the early production of the original Star Wars film, the Stormtroopers were to wield Lightsabers and hand-held shields instead of blasters. Riot Troopers in Star Wars: The Force Awakens, utilize such shields in conjunction with riot batons.
Despite what many people think, only the initial batch and a few, specialized legions of Stormtroopers were clones. After a while, the Empire started recruiting birth-bred humans. However, the Stormtroopers of the 501st Legion (referred to as "Vader's Fist"), utilized by Darth Vader and the Empire since the Clone Wars, were all clones created from the template of bounty hunter Jango Fett.
In April of 2014, the Star Wars canon was retconned so that only the six films, the Clone Wars series, and any future projects (including the sequel trilogy and Rebels, as well as subsequent novels and comics) would be canon to the universe. It was later established in Rebels that, in the new canon, soon after the Clone Wars, all clones were decommissioned and replaced with recruits.
Despite their fierce reputation, the Stormtroopers have usually been depicted as being rather slow, dim and incompetent; they have been easily outwitted many times, and their skills in firearms is rather poor despite being described at one point as being 'so precise'. First Order Stormtroopers have none of these weaknesses.
The armor of the Stormtroopers is much weaker than that of a Clone Trooper.