When Palpatine went out looking for an apprentice, he found Khameir Sarin, a 12 years old Zabrakian, on the planet Iridonia. At that young age, Palpatine began training the young Zabrakian in the ways of the Dark Side of the Force.
Some years later, when Palpatine decided to marry Shmi, Khameir became officially Anakin's babysitter. Yes, you can imagine that this wasn't really what he wanted to do. In fact, the little brat was really getting on his nerves, and the bad habit he had to hit his horn with a plastic hammer toy wasn't helping too. Anakin wasn't stopping to ask him thousands of stupid questions, annoying him and bothering him while he was trying to practice his skills. As Anakin grown up, Palpatine, who, as you know, horribly likes children, asked Khameir to take care of his training. Palpatine wasn't sincerely going to do that. He was busy, he had a Republic to overthrow.
As time passed, Khameir was finally granted Dark Lord of the Sith. He took on an alias, now becoming Darth Maul. Then, he tatooed sith black designs on his body, showing his devotion to the Dark Side.
Darth Maul first appeared to the public during the trade embargo of Naboo. Here, he was the quiet, but ever-dangerous apprentice of Darth Sidious (well, Palpatine...anyway), the menacing influence of the vast Trade Federation. Sensing failure, Darth Sidious sent his Dark Lord apprentice to seek and destroy the two Jedi. The Republic first came to know of Maul only as a mysterious attacker. While Qui-Gon Jinn was escorting the fugitive Queen Amidala from Tatooine to Coruscant, Darth Maul swept down from above, lunging at Qui-Gon from his rocketing Sith speeder. Maul's attack was relentless; he hammered down lightsaber strikes against the accomplished Jedi Master, forcing him back time and again. It was only the timely interception of Qui-Gon by the Queen's Royal Starship that spared him.
An angry Maul, knowing the taste of failure, was then sent by Darth Sidious to Naboo, to keep an eye on the leaders of the Trade Federation. As an undeniable example of his skill and devotion, Maul plunged headlong into battle against two Jedi warriors. Using his double-bladed lightsaber, Maul held off both Obi-Wan Kenobi and Qui-Gon Jinn in the heart of the Theed Royal Palace. When the Jedi became separated, Maul killed Qui-Gon with a well-placed saber strike. Kenobi, enraged, attacked Maul. This barrage was deflected by Maul who used Obi-Wan's touching of the dark side as a conduit for a Force attack; using the Force, Maul pushed Obi-Wan into a deep mining pit. Kenobi held onto an outcropping for dear life. Calming himself by calling upon the light side of the Force, Kenobi was able to surprise Maul, and cleave him in half with his saber.
His death got greatly angry and furious Palpatine, but also Anakin, who started to understand that he couldn't tease anymore his babysitter. He sweared to avenge Maul's death and to kill that jedi who dared to cut his babysitter in two.