During Star Wars: The Phantom Menace, Darth Maul had no clue about Anakin and dismissed him as a child following the Jedi around. But with Maul's return during the Clone Wars, he likely found out about Anakin through his obsession with Obi-Wan.
Darth Vader's true identity as Anakin Skywalker was a highly guarded secret, known only to a select few individuals including Palpatine, Obi-Wan Kenobi, Luke, Han, Leia, R2-D2, C-3PO, Master Yoda, Bail Organa, Ahsoka Tano, Darth Maul, Grand Moff Tarkin, Grand Admiral Thrawn, Jocasta Nu, Ferren Barr, Verla, Reva, ...
Darth Maul and Darth Vader never met in the Star Wars canon, although Maul and Anakin Skywalker were heavily involved in key events of the Clone Wars. That includes the Siege of Mandalore, in which Anakin would have participated had it not been for the Chancellor's kidnapping.
Regardless, based on the season 7 of The Clone Wars, and the fact that Darth Maul was aware of Anakin Skywalker's future and his role as the Chosen One, it is very likely that Darth Maul indeed feared Darth Vader to some extent, and preferred to avoid a direct confrontation with him, at least, on his own.
Originally Answered: Who Knew Darth Vader was Anakin (Canon and Non-Canon)? Vader, Sidious, Yoda, Obi-Wan, Luke, Leia, Han - we know that from the movies. Grand Moff Tarkin knew it too, as did Bail Organa. Ahsoka Tano learned it too during their duel.
Order 66 Extended Cut - The Definitive Edition [4K UHD]
How did Maul know about Anakin?
Maul's power in the Force gave him the ability to have intricately detailed visions of not only what was to come but also what had already occurred. No one knew that Sidious was grooming Anakin to become his Sith apprentice other than Sidious himself.
Despite seeing Vader as an idol, Kylo conveniently ignored his grandfather's redemption. He was well aware of what happened, and it's likely Luke himself who told Ben about the events of Star Wars: Return of the Jedi.
Regardless, based on the season 7 of The Clone Wars, and the fact that Darth Maul was aware of Anakin Skywalker's future and his role as the Chosen One, it is very likely that Darth Maul indeed feared Darth Vader to some extent, and preferred to avoid a direct confrontation with him, at least, on his own.
But two things were standing in Maul's way: he was beyond terrified of Palpatine and knew the Jedi wouldn't trust him. Maul had killed Qui-Gon and numerous other Jedi and started a huge Mandalorian conflict that left thousands dead.
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.
Darth Maul Almost Killed Anakin In The Phantom Menace
Maul could have run over Anakin with his speeder or even hit the Chosen One with a lightsaber, something that was only avoided because Qui-Gon warned Anakin to get down. That said, Darth Maul was probably not aware of how important the boy was.
Yoda's presence on Dagobah was likely hidden due to his mastery of Force Stealth and the planet's connection to the Force. Yoda, with his enhanced Force abilities and potential home-field advantage, would have had the upper hand against Darth Vader if they engaged in a lightsaber duel.
By the time of Episode 3; Anakin is in his prime, and already one of the Jedi Order's most powerful “masters” (although technically still a knight), just behind Obi-Wan, Windu, and Yoda. Maul wouldn't stand a chance. Anakin stomps.
Returning to Dagobah to complete his training, an ailing Yoda told Luke the terrible truth that Vader was his father, Anakin Skywalker. Rather than destroy his father, Luke sought to bring him back into the light. At 900 years old, Yoda passed away, telling Luke that there was another Skywalker.
Obi-Wan Kenobi was Darth Maul's nemesis in Star Wars, but there was a time when a young Anakin Skywalker dueled and defeated the Sith Lord. Before the Clone Wars forced them into military positions, Star Wars' Jedi filled many roles for the Republic.
Calming himself, Obi-Wan leaped over Maul and used Qui-Gon's lightsaber to sever Maul in two. On Dathomir, the Nightsister leader Mother Talzin believed that Darth Maul was alive and in exile somewhere in the Outer Rim.
Like his master, Darth Sidious, better known as Sheev Palpatine, Maul's main weakness was his overconfidence. In Luke Skywalker's confrontation with Palpatine during The Return of the Jedi, he tells the Emperor that his overconfidence is his weakness.
His Sith training made Maul long for revenge against the Jedi Order, which had defeated the Sith a millennium earlier. With his master, Darth Maul hoped to destroy the Jedi and restore the Sith to galactic power. However, Maul's hatred of the Jedi was more personal.
While Maul was later deepened and somewhat humanized by The Clone Wars and Rebels, he remained an evil villain the whole time. Anakin Skywalker was framed as a tragic hero in the prequels.
Why was Maul's death so quickly? He delivered two quick strikes, which Kenobi met, returning his attack only once. It was enough. Maul's weapon was cut in two, as was his chest.
Maul shows signs of Antisocial Personality Disorder and Narcissistic Personality Disorder that were probably caused by a mix of genetics and circumstances.
Maz Kanata's smile as she sees Leia's body pass into the Force only after Ben's death seems to indicate Leia, a true Jedi, knew what her ultimate purpose was in Star Wars: The Rise of Skywalker. It was to save and redeem her son, and in turn, redeem the Skywalker family.
We moviegoers know that Rey learned during her “mindmeld” with Kylo Ren that Kylo is “afraid… that you will never be as strong as… Darth Vader!” Beyond that, we haven't been told what else, if anything, Rey knows about Vader.
At the end of the Skywalker Saga's final chapter, he revives Rey (this is after she spends just about all of her energy defeating Grandpa Palpatine). Then, the two engage in some intense staring, followed by a kiss, and eventually, Solo dies, his body disappearing as he floated away to wherever Force ghosts go.
