Mephiles the Dark (闇のメフィレス, Yami no Mefiresu?) (pronounced [mɛfɨləs] or [mə'fɪliːz] in English) is one of the main villains of the game Sonic the Hedgehog (2006). He is the conscious, mind and will of the Sun god Solaris, ultimately making him the main villain of the game towards the end.
Mephiles is the final boss of Shadow the Hedgehog's story, although he plays a pivotal role in all three of the game's storylines. He is a skilled manipulator, tricking Silver into believing that Sonic was the Iblis Trigger and thus that killing Sonic would save Silver's future. He also has a particular interest in Shadow, who originally imprisoned him after his creation, and whose appearance and powers Mephiles absorbed upon his release. Mephiles repeatedly attempted to convince Shadow to join him, but Shadow refused each time.
He is famous for being the only character in the various Sonic continuities to actually succeed in killing Sonic.
Mephiles has three forms. Its original form was an amorphous mass of darkness. In his second form, Mephiles appears almost identical to Shadow the Hedgehog, aside from having green eyes with slit pupils, no visible mouth (though his muzzle moves when he speaks, as if he does have a mouth), and the fact that everything that is red on Shadow is a pale powder blue on him. His third and most common form was a crystalline, anthropomorphic hedgehog, in this form, he has no visible nose, mouth, or feet.
Unlike most of the villains in the Sonic series, who are driven by a lust for power or revenge, Mephiles (as Shadow put it) only seems to crave destruction. He is portrayed as a cold, ruthless villain with no sense of compassion. He would do anything to accomplish his goals, even if it means taking innocent lives. Mephiles happens to take great pleasure and delight in hurting others and has been shown to have a very warped and twisted sense of humor, making him a very sadistic and psychotic individual. For example, he made it his sole mission to cause pain to Elise throughout the entire course of the game, and even broke out into a maniacal laughter after ending Sonic's life. This is also seen when he taunts Omega by telling him he would be reprogrammed to capture Shadow. Mephiles also happens to be highly intelligent, as he's capable of using and manipulating people to further his evil plans. This is shown when he preyed upon Silver's frustration and desire to save the world, by deceiving him into thinking that Sonic was responsible for everything, knowing that killing him would have done the exact opposite of what Silver was trying to achieve.
He also has nihilistic tendencies, as evidenced in his final fight against Shadow, where he asks why Shadow even bothers fighting at all, and why Shadow even bothers defending humanity when they will inevitably persecute him later.
Mephiles can manipulate and move through time with an ability similar to Chaos Control. His primary offensive technique is a massive sphere of black energy that is spawned from his hands that home in on their targets. He can also use the energy spheres to move himself and others through time. Furthermore, he can alter his physical form to sink into the ground and merge with the shadow of another. He can also manipulate shadows to create "clones" of himself, although they are warped and imperfect without the power of the Chaos Emeralds. He can also merge the clones together to make large shadow monsters. With two Emeralds, he can create an army of perfect clones. As seen in "The Showdown with Mephiles" cutscene, Mephiles can also knock opponents away by firing shockwaves of energy at them. Mephiles's final attack used before transforming into his Solaris form was a long energy bolt (dubbed the "Dark Chaos Lance" by fans) that he extends from his right hand to impale Sonic.
Mephiles appears to be immortal, surviving every fight he takes part in, and whenever he is beaten he seems to just shift into his ooze-like form. Whether or not he is capable of feeling pain is unknown; though he reacts to taking damage during his boss battles with Shadow, he merely stood and allowed himself to be shot multiple times when confronting Omega at Wave Ocean.
Mephiles is also a highly skilled manipulator, as he was able to easily manipulate Silver and Blaze to nearly get his desired result.
Mephiles has also demonstrated the curious ability to, with one Chaos Emerald in his possession, warp the other six Emeralds to his location instantly, which he did after the Flames of Disaster were released from Elise and before reuniting with Iblis.
He is also shown to have adept knowledge on using modern technology, as evidenced by his knowing exactly which files in Dr. Eggman's computer to use when trying to persuade Silver to assassinate Sonic the Hedgehog. This is most likely due to his apparently endless lifespan and time travel power allowing him to study the world around him for as long as he needs to.