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.
Ahsoka Tano, a Togruta female, was the Padawan learner to Anakin Skywalker and a hero of the Clone Wars.
Galen Marek (pronounced /ɡeɪlən ˈmæɹɛk/), codenamed Starkiller, was a Force-sensitive human male assassin of the Sith Order and agent of the Galactic Empire as the secret apprentice of the Sith Lord Darth Vader.
Not anymore, but in Legends, before Disney declared it to not be canon, Darth Vader had 2 apprentices. In The Force Unleashed and The Force Unleashed II, he trained both Starkiller and Galen Marek (not the same person, the latter was a clone of the former).
Darth Maul became apprenticed to Darth Sidious while still a child. Darth Tyranus and Darth Vader, both former members of the Jedi Order, became Sidious' apprentice, in turn, as adults.
Character information
Ben is the son of Han Solo and Leia Organa, the nephew of Luke Skywalker, and the grandson of Anakin Skywalker and Padmé Amidala. After turning to the dark side, he becomes the apprentice of Supreme Leader Snoke, and later renames himself Kylo Ren upon becoming the Master of the Knights of Ren.
Darth Sidious was always stronger than Vader, which is why he ruled over him for almost 20 years and turned him into the Sith Lord he was.
Because he was not an active member of the Jedi Order during Order 66, Infil'a escaped execution. Some time later, he faced the Sith Lord Darth Vader wielding a green lightsaber. Infil'a put up a fierce fight against Vader, almost killing him by throwing the Sith Lord off of a cliff.
During the Imperial Era, a Pau'an Jedi hunter served as the Grand Inquisitor. During the Age of the Empire, the title was held by a Pau'an male selected by the Emperor, Darth Sidious, to stand by his apprentice, Darth Vader.
Darth Vader
Of course, Darth Vader is the most important apprentice of Darth Sidious. Anakin Skywalker was a young boy when Palpatine began building a relationship with him, working behind-the-scenes to ensure the "Chosen One" would join the Dark Side when the time came.
The Rule of Two created a powerful dynamic by limiting the Sith to only one master and one apprentice at a time, although not all Sith followed the rule as some took apprentices of their own while still serving a master.
Who is stronger prime Vader or Luke? Canon-wise, Vader wins this by a landslide. His power and knowledge in the force increased significantly which made Palpatine himself fear that Vader would overthrow him.
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.
Born in 102 BBY during the High Republic Era, Dooku was taken by the Jedi Order after being abandoned by his family and learned the Jedi arts as the Padawan of Yoda, the legendary Grand Master of the Jedi Order.
Anakin Skywalker
A fittingly unconventional Jedi mentor for an unconventional padawan, Ahsoka spent most of her training with Anakin and was this influenced by him the most.
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.
It appeared that Darth Vader was more machine than we thought. 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.
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?
In recognition of Anakin's efforts in the war, he was given the title of Jedi Knight.
Darth Vader is Clearly the More Powerful Force User
Between Darth Vader and Obi-Wan, it's pretty clear that Vader is far more powerful with the force. After all, he pretty easily used the force to stop a starship from taking off in the previous episode, and manhandled Kenobi throughout the majority of the show.
A master of the Force and a seeker of arcane lore, Snoke seduced young Ben Solo when the Force-sensitive boy desperately needed a teacher. Snoke's influence would prove critical when Luke Skywalker finally agreed to make Ben one of his new Jedi apprentices.
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.
Growing up, Solo was unaware of his Sith heritage as the grandson of Darth Vader. Only his parents and uncle, Jedi Master Luke Skywalker, knew the truth of Anakin Skywalker's past.