Darth Vader defeats Darth Maul. The two Sith Lords engaged in a lightsaber duel, going through the volcano and onto a bridge situated over a river of lava, which collapsed, though they both survived and continued their battle.
In the end, Vader reigns supreme against the reborn villain as his hatred drives him to be named the winner of the fight. In the end, Darth Vader's inner hatred and darkness made him the winner of the epic battle against Darth Maul.
Darth Maul knew that Anakin Skywalker was the so-called Chosen One, and that he had been groomed by Darth Sidious to become his new apprentice, Darth Vader.
Yep. Darth Maul didn't really say or show straight up that he "feared" Darth Vader, but he openly stated his belief that he could not defeat Darth Vader without the help of the Jedi, therefore on his own.
Although they didn't interact with each other, Anakin Skywalker first met Darth Maul on Tatooine during the events of The Phantom Menace and then later on in the film on Naboo.
In the film's climax, Maul duels Qui-Gon and his apprentice Obi-Wan Kenobi (Ewan McGregor). He is able to kill Qui-Gon and knock Obi-Wan down a shaft, but Kenobi propels himself out of the pit and uses Qui-Gon's lightsaber to bisect Maul, sending the two parts of his body falling down the shaft.
Galen Marek, codenamed Starkiller, was the son of a Jedi fugitive killed by Vader during the Great Jedi Purge. After his father's death, he was trained by Vader since childhood to become the Sith Lord's secret apprentice.
Appealing to the hate and conflict within him, Darth Sidious goaded Luke into attacking. Vader defended the Emperor and he and Luke were locked in mortal combat. Luke lost control of his anger, viciously attacking Vader, finally beating him down and chopping off his hand with his lightsaber.
1/15 Luke Skywalker
Having faced his father once before, Luke was familiar with his tactics and used the force to gain an upper-hand. In Star Wars Canon, only Luke Skywalker can be acknowledged as the one who truly defeated Darth Vader.
This information comes to light form the comic series Darth Vader: Dark Lord of the Sith by Charles Soule and Giuseppe Camuncoli, in particular issue #7. Palpatine admits to Darth Vader that the Jedi he actually feared most was none other than Jocasta Nu.
Considering his infamy, it's hard to deny that Darth Vader is the more powerful of the two, but his victory over Maul wouldn't come easily. As the Emperor's enforcer, Vader is terrifying.
Despite learning that his Master took a new apprentice, Darth Tyranus, Maul still believed that he was a Sith Lord. Taking his brother as an apprentice, Maul and Opress held that they were the true Sith rather than Sidious and Tyranus.
Maul did intend to draw Obi-Wan to Mandalore and he counted on Anakin Skywalker coming as well. Through his vision of the future, Maul realized Anakin was the key to Palpatine's plans. He intended to kill Anakin on Mandalore, thus throwing a major wrench in Palpatine's schemes.
Maul, however, soon lost the Darksaber when Darth Sidious defeated him in combat and sent him away to prison on Stygeon Prime.
Due to his proficient skills within the force, Yoda is also an incredibly skilled lightsaber combatant. He is one of the highest-ranking Jedi in the Jedi council. Because of his Force sensitivity, Yoda would easily be able to evade Maul's attacks.
Yes, he might be able to physically beat Vader, but what would that achieve? Vader is the chosen one, so Yoda mustn't kill him. True victory can only be achieved by turning him good again. Obi-wan, the second-closest person to Anakin, failed on the lava planet.
Vader held respect for Tarkin which is clearly shown and the only case in which Tarkin outranked Vader would be the case in which Vader was in the Death Star or within Tarkin's Oversector which he likely was as Tarkin was Grand Moff of the Outer Rim Oversector, the largest one.
His armor could be hacked and controlled by a device. In a turn of events, Darth Vader's right limb holding his dangerous scarlet lightsaber was moving of its own accord toward his neck. This was a dangerous weakness indeed.
Darth Sidious
In the end, Vader managed to fulfill the prophecy tied to him. As for Darth Sidious, he's by far the most dangerous enemy Vader has had. Becoming emperor of the galaxy and crushing most of the Jedi was proof enough.
Admiral Ozzel : [appearing onscreen with Captain Piett] Lord Vader, the fleet has moved out of lightspeed and we're preparing to... Darth Vader : You have failed me for the last time, Admiral! Captain Piett?
Did Darth Vader ever lost a fight? Darth Vader is one of the greatest villains of all time. But even he gets beaten sometimes. CBR lists all of the folks who managed this improbable feat!
Yoda held the title of Grand Master of the Jedi Order since the days of the High Republic Era. At some point, Yoda took on a human named Kantam Sy as his Padawan. The two were stationed at the Jedi Temple on the planet Endovar.
Eventually, he lost both his legs and his remaining arm in the climactic duel on Mustafar between both he and Obi-Wan. As Vader, he had each limb replaced with cybernetic parts, but would lose his robotic right arm one last time when Luke Skywalker faced his father in Return of the Jedi.
A Sith Lord with the ability to prevent death and create life, Plagueis is the mentor of Sheev Palpatine/Darth Sidious, who, in accordance to the Sith's Rule of Two, eventually betrays Plagueis by murdering him in his sleep, taking his place as Sith Master.