Dooku voluntarily left the light side behind and became Darth Sidious' dark side disciple, taking the secret name Darth Tyranus and leading the Separatist army. Dooku advanced Sidious's secret plot to take over the galaxy, but forgot that betrayal is the nature of the Sith.
Also he was part of the separatists because he wanted them to win the war and wasent really botherd about taking over the Galaxy like Palpatine was, because of the fact that he wasn't fully committed to the ways of the dark side he preferred to use his title of count dooku as his name rather that his sith one of Darth ...
On more than one occasion, he even offered his hand to Obi-Wan and told him outright who the Sith Lord was that the Jedi have been searching for. Bottom line, Dooku never considered himself a Sith. And he wasn't; he was a man looking to change the galaxy in a way the Jedi were unwilling to try.
His first name was Dooku. He was a noble and the sitting ruller of hiw homeworld of Sereno, so he was Count Dooku of Serenno, Serenno was the name of both his planet and of his Noble House, so if something Serenno would be his last name if he ever were to get one, which he didn't.
While Dooku was certainly evil -- and even had a Darth sobriquet, Tyranus, that he rarely used -- he was never quite a Sith, at least not in the true sense. Unlike those who espoused the Sith doctrine, Dooku wasn't motivated by hatred or fear, but by the same purpose that drove him as a Jedi.
Palpatine, pretending to be a helpless bystander, goads his future apprentice on. “Do it!” he hisses. Skywalker does, beheading Dooku as he gives in to his base emotions. He almost immediately feels regret, but Palpatine works to dismiss it.
Anakin gives in to his hatred of Dooku and uses his anger to overpower him, severing both of Dooku's hands and leaving him helpless. Palpatine then orders Anakin to execute Dooku on the spot, thus betraying Tyranus. After initial hesitation, Anakin decapitates Dooku, much to his horror of the betrayal by his master.
Over the next decade, the galaxy was on the verge of civil war with entire star systems—led by Count Dooku, Yoda's one-time Padawan—threatening to secede from the Republic by 22 BBY.
Padawan Windu was trained in the ways of the Force by Jedi Master Cyslin Myr.
The story centers on Jedi Master Mace Windu as he attempts to rescue his former Padawan, Depa Billaba, from his homeworld, Haruun Kal.
Within the Star Wars Legends continuity, Yoda's Jedi instructor was N'Kata Del Gormo, a Hysalrian Jedi Master, according to an in-universe legend.
Studying Jedi Archive records, Dooku based his new weapon design after the curved hilts that were standard during the heyday of Form II lightsaber combat. The curve allowed the hilt to fit better into his hand, allowing for superior finesse and precise blade control.
The reason Dooku joined the Separatists, he said, was that he learned a terrible truth: a Sith Lord called Darth Sidious controlled the Senate. With Obi-Wan at his side, they could destroy the Sith.
Vader's own grandson, Ben Solo/Kylo Ren, would follow in his grandfather's dark side footsteps to make the dark side supreme. However, Kylo Ren never took on the name of Darth, even though he worshipped everything about the Sith that came before him.
1 Darth Sidious
As well as being a gifted bladesman Sidious' connection to the Dark Side is extremely powerful, granting Sidious the ability to conduct force lightning.
Darth Maul
Dooku despises Maul for being a threat to him, and for killing his beloved padawan Qui-Gon, and Maul hated Dooku for being his replacement. They also didn't regard each other as a true Sith: Dooku saw Maul as nothing more than a trained animal and Maul saw Dooku as a Sith pretender.
Yoda was a legendary Jedi Master and stronger than most in his connection with the Force. Small in size but wise and powerful, he trained Jedi for over 800 years, playing integral roles in the Clone Wars, the instruction of Luke Skywalker, and unlocking the path to immortality.
Qui-Gon Jinn was a respected, independent Jedi Master who first located and identified Anakin Skywalker as the Chosen One foretold in the Jedi Prophecy. Born on Coruscant circa 80 BBY (Before the Battle of Yavin), Qui-Gon trained as a Padawan under Jedi Master Count Dooku.
Master Yoda has risen above all others to claim the top spot as the most powerful Jedi of all time and the true chosen one according to IGN's audience. He won pretty handily as well, as he was victorious in 89,756 of his 95,243 battles and had a win percentage of 94.2%.
Indeed, Palpatine seems to have seen Maul as an ideal apprentice, admitting he was "a loss" compared to Dooku in Darth Vader #20.
Obi-Wan discovers that Qui-Gon's old master, Count Dooku, has become a Sith Lord; and Dooku mentions Qui-Gon as he interrogates a captured Obi-Wan, expressing grief over his former apprentice's death and debating that Qui-Gon would have followed him in leaving the Republic had he survived.
With a potential Jedi Code-defying love affair with another Jedi, Dooku is more of a foil to his Clone Wars-era enemies, Anakin Skywalker and Obi-Wan Kenobi, with Dooku's lover, Jedi Master Jocasta Nu, possibly retaining feelings for Dooku well after he joined the ranks of the Lost Twenty.
It's not shown, but it is clearly insinuated that Anakin killed the younglings. This is confirmed later in the movie when Obi-Wan informs Padme that Anakin killed them. Both are torn apart with hurt and confusion, trying to make sense of something so terrible. How could Anakin do such a thing?
Having covertly turned Kylo Ren—Anakin's grandson and Luke's nephew—to the dark side, Palpatine orders Ren to find and kill Rey, the last remaining Jedi and Palpatine's paternal granddaughter. Palpatine is ultimately defeated and destroyed by Rey.
In Star Wars canon, there are currently only four younglings that are known to have survived the infamous Order 66 and Darth Vader's slaughter, while in Legends, there are 20 known survivors.