Few people set out to become a Dark Lord of the Sith. When the Jedi Order finds someone who is Force-sensitive, they tend to teach them the better aspects of the light side of the Force while disparaging the dark side as much as possible. When someone is taken directly into the Sith, it's often at a young age when they are easily corrupted. The most dangerous people to become Sith have always been those who received some training first as a Jedi and then decided it would be best to pop on over to the dark side to see what all the fuss was about (word is they have cookies).
Despite all the warnings from elder members of the Jedi Council and a little green wizard, people still try out their skills for the Sith and we have gone through all of canon and the newly-labeled Legends to find the most powerful members of the Sith who were once a Jedi (they are listed in no particular order). So, after much contemplation and argument, here are the 15 Most Powerful Jedi Who Turned To The Dark Side
15 Darth Vader (Canon)
Vader began as Anakin, an adorable little boy who grew up on the Hutt planet Tatooine with his mother. He was rescued from slavery by Jedi Master Qui-Gon Jinn and his apprentice, Obi-Wan Kenobi. Anakin was initially refused training by the Order so Qui-Gon decided to foster the boy but was killed before he could begin his training - despite the Council's wishes. It fell to Obi-Wan to train Anakin, which he did. Anakin's arrogance and love for his secret wife, Padmé, and her unborn child(ren) were used against him by Darth Sidious in his plans to become the Emperor of the galaxy. Anakin was convinced everyone he loved would die so he agreed to train under Sidious as his apprentice, Darth Vader and rebelled against the Jedi Order.
He killed the younglings in the Jedi Academy and went on to hunt down and kill all of the remaining Jedi he could find. With Sidious now sitting as the Emperor of the galaxy, Vader was used as his muscle. He was by far one of the most feared Dark Lords of the Sith, but he eventually brought balance to the Force by killing his master and embracing the light that was still within him. In the end, he became one with the Force.
14 Darth Malak
Malak joined the Jedi Order following the destruction of his home which turned him into a young refugee. When the Mandalorian Wars began, he defied the Jedi Council and joined with the Old Republic's starfleet. He rallied more Jedi to his caused and defeated the Mandalorians in each engagement. The conflict took him outside the Rim into uncharted space where he found the Star Forge, an ancient Rakatan machine.
Malak became corrupted by the Dark Side energies present on Malachor V, a forgotten Sith world. He, alongside his longtime comrade and fellow Jedi, Revan, succumbed to the Dark Side and founded a new Sith Empire. In true Sith fashion, Malak rebelled against Revan, who had become his master and the Dark Lord of the Sith. Using a Republic strike team's attack as an opportunity, he took the place of his former friend and master to name himself the Dark Lord. He retained his power using the Star Forge, an ancient space station that utilized the power of a star to fuel it and the creation of its ships and weaponry.
Malak was finally killed by his former master Revan in a lightsaber battle. His final words were "And in the end, as the darkness takes me, I am nothing."
13 Exar Kun
Exar Kun was an arrogant young Jedi who would engage in "friendly" sparring with his fellow Padawans. His anger and rage would rise to the surface in these bouts and his quest for power and knowledge of the Dark Side concerned his master and the rest of the Jedi Order. Kun's arrogance manifested with his determination to learn aspects of the Dark Side while remaining a Jedi; a path that would directly lead him to the Dark Side of the Force. Though his master tried everything to keep his Padawan from learning the Dark Side, Kun, in his arrogance, ignored and abandoned his master. He declared himself a Jedi Knight and continued to attest his ability to remain in the light while still practicing and learning about the dark.
Kun proceeded to Korriban and followed the advice of Sith spirits, who embraced Kun as a potential asset. Through various trials and the acquisition of powerful artifacts, Kun finally embraces the Dark Side and becomes a Dark Lord of the Sith. His powers grew as he took on an apprentice, but Kun was eventually faced with capture by the Jedi and separated his spirit from his body. He was trapped by the Jedi in his temple on Yavin IV for thousands of years.
12 Ulic Qel-Droma
Ulic was one of several Jedi in training under Master Arca Jeth on the planet Arcania. His father was a Jedi Master and he showed a significant affinity to the Force as well as lightsaber combat, but like many on this list, he was an arrogant youth. In his first mission as a Jedi, he and his fellow students attempted to quell a civil war on the planet of Onderon. They uncovered a sinister dark side plot by Sith Lord Freedon Nadd that left his progeny as the ruling leaders of the planet. They battled against the Sith Sorceress Queen Amonoa with the help of their master.
When Ulic decided to infiltrate the Krath in order to learn their secrets, the other Jedi opposed the idea as it was too risky. Ulic eventually killed the leader of the Krath but refused to leave. When he battled the Sith who killed his master, a great Sith spirit arose and claimed both for the dark side, making Ulic an apprentice to Exar Kun, the Dark Lord of the Sith.
11 Darth Ruin
Phanius was a member of the Jedi Order but was considered something or a rogue or renegade Jedi Master. He sought to learn as much as he could but conflicted with the Order over teachings they kept secret or prohibited outright. Because of this conflict, he left the Order and brought together a number of disjointed Sith clans into a new Sith Empire. 50 Jedi Knights would join him in his new order in what would be called the Fourth Great Schism. He and his followers embraced the dark side of the Force and he rechristened himself Darth Ruin, a Dark Lord of the Sith.
Ruin and his followers initiated the New Sith Wars against the Jedi Order and the Galactic Republic, but due to infighting and his single-minded ambitions, his followers rebelled against him. He was ultimately killed by the Sith he led as his new Sith Empire disintegrated underneath his command. Ruin and his exploits took place two thousand years prior to the events depicted in Star Wars: The Phantom Menace and the subsequent films.
10 Darth Traya
Kreia started out as a historian and Jedi Master who was exiled by the Jedi High Council after her students followed Revan into battle in the Mandalorian Wars. Kreia followed Revan to a Sith world where she discovered the Trayus Academy and turned to the dark side of the Force. She became Darth Traya, a Sith Lord. Traya sought out and found Darth Nihilus and Darth Sion with whom she formed the Sith Triumvirate. The group was intent on destroying the Jedi.
Things didn't work out so well in the Triumvirate; Traya was overthrown and cast out by her former comrades. Angered after being exiled by the Jedi and the Sith, she then sought to rid the galaxy of the Force. She turned Jedi Master Atris to the dark side and eventually defeated Darth Nihilus. Former Jedi General Meetra Surik found Traya in the depths of the Trayus Academy on Malachor V and defeated her in a lightsaber duel.
9 Darth Caedus
In a stor that has now been relegated to Legends, Jacen Solo was one of the children of Han Solo and Leia Organa. He was a powerful Jedi Knight who rebelled against his family and the Jedi to embrace the dark side of the Force. Solo's desire to return the galaxy to order following the Civil War was what led him to the Dark Side. He embraced whichever methods proved useful in the attainment of his goal, which led him down the path. He rechristened himself Darth Caedus and agreed to become the apprentice of Lumiya, a Sith.
As Caedus, he began to turn into a much darker version of himself. He seized control of the Galactic Alliance and even killed Mara Jade Skywalker, Luke's wife. He tortured his former apprentice, Ben Skywalker, and took on a new apprentice as a Sith called Tahiri Veila. He continued to grow in power until he was finally stopped by his twin sister, Jaina, who was able to kill him in a lightsaber battle. Unlike his grandfather, there was no redemption for Jacen Solo.
8 Kylo Ren (Canon)
Ben Solo was born a year after the Battle of Endor to his mother, Leia Organa and his father, Han Solo. He quickly showed a force sensitivity akin to his uncle, mother, and grandfather and was inducted into the new Jedi Order as a trainee under his uncle, Jedi Master Luke Skywalker. Ben was often left to his own devices by his parents who were somewhat busy trying to put the galaxy back together following the war. This feeling of abandonment would become useful to Snoke, a powerful figure who recognized the potential in Ben and helped foster him into the dark side of the Force.
Ben embraced the Dark Side and destroyed the new Jedi Order. He rebelled against his uncle and killed the other trainees in the school, forcing Luke to abandon the fight and seek exile and the original Jedi Temple. As his powers grew, Solo became a member of the Knights of Ren, under the influence and tutelage of Supreme Leader Snoke. He would finally embrace the dark side fully by killing his father, Han Solo, on Starkiller Base before being seriously injured by Rey in a lightsaber duel. Kylo Ren first appeared in Star Wars: The Force Awakens in 2015.
Revan was one of the most powerful members of the Jedi and ultimately, the Sith who lived nearly 4,000 years prior to the Battle of Yavin as depicted in Star Wars: A New Hope. Revan became a central figure in the Mandalorian Wars who would sacrifice his morals to achieve victory at any cost. Revan began to study the ways of the Sith after finding a vast cache of Sith artifacts on Malachor V. Revan embraced the dark side believing it would help him to achieve victory more easily, though he kept this secret. He engaged in a massive battle between the Jedi and Mandalorians where he was able to kill Mandalore the Ultimate and activated a weapon that destroyed the surface of the planet.
Shortly after saving the galaxy, he returned with an army of fallen Jedi and began the Jedi Civil War. He established a Sith Academy and became a Dark Lord of the Sith with Malak as his apprentice. He was eventually captured and had his memory erased so that he returned to the light side of the Force. He became a true enemy of the Sith and sought to remove the Sith Emperor from the galaxy.
6 Darth Tyranus (Canon)
Count Dooku was one of the central players in the events that led to the Clone Wars. He was originally the Padawan of Yoda but clashed constantly with his master as well as the Jedi High Council, which led him to resign from the Order. When his apprentice, Qui-Gon Jinn was finally killed in battle, he lost his faith in the light side of the Force and became the apprentice to Darth Sidious and was called Darth Tyranus. He became a detached and much colder man at this point, when he formed the Confederacy of Independent Systems. The Confederacy was a separatist group intent on rebelling against the Republic.
All of his machinations seemed to be part of the overall plot to begin the Clone Wars. This is what led to the placement of Sidious as the Emperor of the Galaxy now that the former Republic's democracy was pretty much at an end. Though he was a trusted ally and faithful servant of his master, Sidious betrayed Dooku and engineered a plot to have him killed by his true apprentice, Anakin Skywalker. In a fit of rage, Anakin succumbed to his anger and decapitated Dooku, seemingly saving the Emperor in the process.
5 Darth Krayt
A'Sharad Hett was raised by the Tusken Raiders on the planet Tatooine, where he was trained in ways of the Force by his father, Shared Hett. When his father was killed, he resumed his training under Ki-Adi-Mundi until finally becoming the apprentice to The Dark Woman, the same master who trained his father.
When the Clone Wars began, Hett fought as a General in the Galactic Republic, where he commanded a Jedi starfighter. He became friends with fellow Jedi Anakin Skywalker after the apparent death of Obi-Wan Kenobi at the Second Battle of Jabiim. When Order 66 was given commanding the clones to kill their Jedi Generals, Hett was able to survive and return to Tatooine. He went on to try life as a bounty hunter, which is how he ended up on the planet Korriban.
On Korriban, Hett discovered a Sith Holocron and learned the ways of the dark side of the Force. He did this to hopefully defeat Vader and Sidious, but after learning that this task had already been completed by Luke Skywalker and his pals, he decided to establish a new Sith Order called the One Sith on Korriban. It was at this time that he took on the name Darth Krayt.
4 Karness Muur
More than 7,000 years before the Battle of Yavin, during the time of the Old Republic, Karness Murr was a powerful Jedi Knight. He fought alongside the Dark Jedi against the Jedi during the Hundred-Year Darkness and was exiled alongside his compatriots following their defeat. After discovering the race known as the Sith and establishing themselves as Lords on the planet Korriban, Muur spent most of his time working to perfect his dark side abilities. He became a proficient user of Sith magic and learned to alter other lifeforms.
Muur had in his possession a powerful Sith amulet imbued with dark side power. The amulet enabled Muur to transform living beings in close proximity into mindless thralls called Rakghouls. He built himself an army of Rakghouls with the intention of ruling the galaxy. Muur was eventually imprisoned in his a talisman, which became an even more powerful Sith artifact. After thousands of years, the Muur Talisman came into the possession of Darth Vader, who considered using it against his master.
3 Freedon Nadd
Freedon Nadd studied to become a Jedi under his master, Matta Tremayne during the time of the Old Republic. He continued to lust for greater power than his master felt appropriate so he finally killed his master and abandoned the Jedi. He sought out Naga Sadow's tomb and trained as a Sith under the Dark Lord. He learned many powers only a Sith could wield and once he felt he had learned enough, he killed Sadow and became even more powerful than his former master. Freedon Nadd was so powerful with the dark side of the Force that he didn't let death stop him in his desire for power and glory.
As a spirit, he led an uprising against the Jedi but was stopped by Ulic Qel-Droma when he was still a member of the Jedi. Following this defeat, Nadd decided to train Exar Kun, a young Sith and former member of the Jedi Order, though this would come to be his downfall. Kun followed in his master's footsteps and acquired several amulets and Sith artifacts he was able to use to finally kill Freedon Nadd's spirit, removing him from the galaxy forever.
2 Ajunta Paal
Ajunta Pall was a member of the Jedi Order who rose through the ranks to first become a Jedi Knight and finally, Jedi Master. He was incredibly adept at the study of alchemy and even discovered the secret for creating and shaping life via the Force. The Jedi Order feared this newfound power and declared it an abomination of the Force. The Jedi High Council went so far as to bar Pall's teachings and his followers, calling them all pawns of the dark side of the Force. Pall wasn't too happy with the Order's reaction to his discovery so he and his followers declared war on the Order. Thus began the period known as the Hundred-Year Darkness, which saw the conflict escalate across the galaxy.
The battle raged on, but Pall and his Dark Jedi were defeated. They were exiled from known galactic space until they founded their Empire on the planet Korriban, the homeworld of a Force sensitive species known as the Sith. Pall's power continued to grow as he built the original Sith Empire, which he ruled as the first Dark Lord of the Sith. Following his death, his spirit possessed his tomb. Centuries later, he would let go of his pain and long to return to the light and become one with the Force.
1 Luke Skywalker
Yes, you read that correctly. In the Dark Empire comic book series published by Dark Horse Comics in 1991, Luke strays from the light. After the Battle of Endor and the destruction of the second Death Star, Luke finds himself aboard an imperial prison ship being taken to Byss. He arrives and is taken to a chamber where he meets none other than Darth Sidious, otherwise known as the recently-killed Emperor Palpatine. Luke learns that as soon as he was killed, he transferred his mind into the body of the clone standing before him. Realizing that there was no way he could kill Sidious, Luke reluctantly agrees to become his new apprentice, which is what Sidious wanted all along.
Luke becomes his right-hand man and even stands beside him when Leia is brought before the Emperor. She had attempted to save him, but ran into problems and had to flee without her brother. Luke turns on his new master and destroys the clone tanks, but fails to kill the Emperor, who possesses a living clone and subdues Luke. Leia is finally able to rescue her brother from the clutches of the dark side when she convinces him to help her turn against the Emperor by pushing a Force Storm at him.
Did we forget any of your favorite former Jedi who became powerful Sith Lords? Sound off in the comments and let us know who you would like to see featured on a Star Wars list!