Darth Vader still remains the most popular villain in cinematic history, and he's got a lot of things going for him, including a list of specific character traits unique only to him. Some of these traits are obvious while others are more subtle, and related to his body language. Whatever the case, they are telltale signs that identify the character.
Many of these traits were created when Anakin Skywalker fell to the dark side and became the dreaded Sith Lord fans know and love. Others were either carryovers from his previous life or mirror images of the traits he used to hold as Anakin Skywalker. All of them make him the definitive face of Star Wars.
Heavy Breathing
Vader's most obvious signature trait is his heavy breathing, a side effect of the mask and breathing apparatus he was forced to wear, after sustaining critical injuries in a fight with Obi-Wan Kenobi. This catastrophe led to him becoming the dreaded Sith Lord, and he used his new look to intimate those in his presence.
The breathing sound might be a necessity in order to stay alive, but he's clearly used it as a means to strike fear into others. It isn't known if the mask was devised to give off this particular sound on purpose, but it's a factor that Vader had blended successfully into his most popular character traits.
Clutching His Belt
Vader has a funny habit of sinking his thumbs behind his belt and clutching the exterior with his hands. He tends to do this when talking to his fellow officers, or in the midst of other conversations.
Most Star Wars fans don't really think it's worthy of note, but it's an interesting character trait that deserves a mention. It's the closest to relaxed that Vader ever looks at any given moment, suggesting that he's thinking about something else besides slaying Jedi.
He'll Sacrifice Men For The Mission
Vader had no true friends to speak of, which meant that he viewed his men with total disregard. This was in stark contrast to his earlier life as Anakin Skywalker, where he would charge into battle to save Clone Troopers under attack by Separatist forces.
To Vader, his men were nothing but a resource to be deployed in pursuit of his goals. He would throw entire battalions and squadrons at a problem in order to get what he wanted without batting a lash.
Killing His Staff
Vader doesn't tolerate failure, and his subordinates know it. When push comes to shove, he'll simply kill them and promote some other unfortunate soul to take their place. Working under Vader is an unenviable plight, and most who find themselves in service to the Dark Lord don't last very long.
Even the smallest oversight or fumble can lead to death, and it doesn't matter if the officer was to blame or not. Vader's anger causes him to take out his frustrations on his own officers, some of whom probably didn't deserve to die. It's possible that Vader burnt through his available resources, which might have cost him.
Force Choking
Few were as proficient in the ways of the Force as Vader, and his ability to harness his rage and use it to tap into the dark side was frightening. The Sith Lord could pull off all kinds of catastrophic Force attacks, but he tended to rely on classics like the choke.
Vader liked stretching out with the Force and choking his enemies to death. Sometimes, he would use it as a deterrent in front of others who might oppose him or simply to put a little humility into arrogant officers. Most times, however, he'd use it to slay his enemies, usually in brutal fashion.
Total Lack Of Humor
The Sith weren't renowned for their sense of humor, but not all of them had hearts of pure stone. Even Darth Sidious found time to cackle maniacally while cracking bad jokes at the expense of his enemies. Vader, however, was all business, all the time.
His self-loathing and nihilistic overview probably had a lot to do with it, as Vader didn't really have much to look forward to in life. Those who attempted to get on his good side with light-heartedness were quickly put in their place, and he didn't take kindly to others who attempted to make light of a situation.
Sucking Up To His Boss
Vader bossed around the majority of the Galactic Empire, operating with very little oversight and a lot of power. However, there was one person he didn't dare cross — his Sith Lord master, Darth Sidious.
Secretly, Vader hated Sidious, blaming him for the events that led to Anakin's fall to the dark side and his physical disfigurement. However, he was a master at sucking up, showing Sidious unparalleled respect and devotion in an attempt to stay on his good side. In the background, however, Vader was secretly scheming up a way to supplant Sidious for control of the galaxy.
He Is Tenacious
Vader's strongest character traits were his tenacity and his willingness to go to any length to get what he wanted. When the Millennium Falcon hid out in a dense asteroid field following the evacuation of Hoth, Vader stayed the course in an effort to apprehend them.
Entire ships were destroyed in the process, yet Vader refused to relent. This was part and parcel of his stubbornness and tenacity, no matter how badly the odds were stacked against him. Once the chase was on, Vader never let up until his quarry was caught.
Backing Out On His Deals
A deal with Darth Vader meant that only he would benefit when the deed was done. Across the board, Vader would promise a lot, then either back out of the deal or change the terms and conditions as he saw fit.
The most obvious example was when he brokered a deal with Lando Calrissian to capture Princess Leia and Han Solo on the world of Bespin in Star Wars. Several times throughout the course of the deal, he changed the terms without notice. Those who thought Vader would live up to his word quickly realized how wrong they were.
He Is Quite Arrogant
Anakin Skywalker was always an arrogant boy, and that became worse when he grew into a young man. By the time he'd reached adulthood, this arrogance was affecting his Jedi training. With some subtle persuasion on the part of Darth Sidious, the seeds were planted, and Vader was inevitably born.
As the Sith Lord, Vader was extremely arrogant, believing himself superior to all those around him. In truth, this superiority complex was created out of necessity in order to deal with the massive inferiority complex and self-loathing that Vader felt inside. Arrogance was a way to mask his pain, which ended up being a very destructive coping mechanism.