Solaris is a super-dimensional being that serves as the final boss and true main antagonist of Sonic the Hedgehog (2006). This creature was long-worshipped as a sun god by the people of the Soleanna Kingdom, but little did they know that it was, in fact, a malevolent force capable of manipulating time and threatening the existence of all things. Initially, Solaris existed in the material world as a tiny white flame, but would be split into two separate entities which, over the course of the game, would attempt to re-unite and threaten to destroy the world.
Ten years prior to the events of Sonic '06, Solaris existed as a tiny white flame. Its exact origins were unknown, but it was held in the care of the royal family of Soleanna for many years up until the reign of the then-Duke of Soleanna who attempted to harness the flame's power to control time. As far as the public of Soleanna were aware, the Solaris Project was a plan to create free clean energy, but the Duke wished to harness the power of time control in order to help rewrite humanity's history and erase many of its mistakes. On a more personal note, the Duke wished to restore his daughter's mother to life.
The Solaris Project ended in catastrophic failure as Solaris became unstable and refused to listen to the Duke's commands, splitting into two distinct entities: Iblis, which represented Solaris' raw power, and Mephiles the Dark which represented Solaris' intelligent mind and malicious intent. The two halves of Solaris were captured and sealed away thanks to the hedgehogs Shadow and Silver who had travelled back in time to discover the truth regarding the events that were unfolding ten years in the future. Mephiles was contained within the Scepter of Darkness while Iblis was sealed within the soul of Princess Elise herself. Before dying from wounds caused by the accident, the Duke told his daughter to grow up to be a strong queen who would never cry as doing so would destroy the seal on Iblis.
Ten years later, the scientist Dr. Eggman had discovered the Solaris Project and intended to restart it, hoping to use the power of the Flames of Disaster to take over the world and rule over time. Because of Eggman's actions, Mephiles would be released from the Scepter of Darkness and attempt to rejoin with Iblis, beginning a chain of events spanning three different time periods that would ultimately lead to the death of Sonic the Hedgehog which would cause Princess Elise to cry and allow Iblis to re-emerge. With the Chaos Emeralds' power, Mephiles and Iblis re-united and formed Solaris again.
The reformed Solaris plunged the world into darkness as it prepared to consume all existing timelines. Caught inside Solaris' space-time rift were Princess Elise, Dr. Eggman, Shadow, Silver and all of Sonic's friends, who all worked together to try and retrieve the Chaos Emeralds scattered throughout the rift in order to resurrect Sonic and stop Solaris from destroying everything. The group were successful and Sonic returned to life, and he along with Shadow and Silver used the Chaos Emeralds to transform into their Super forms and battle Solaris in the past, present and future.
The super-powered hedgehogs managed to defeat Solaris by destroying its consciousness, and it reverted back to its original form, a tiny white flame. Sonic and Elise found themselves spirited back to the day before the Solaris experiment took place and saw Solaris' flame, realizing they had the opportunity to erase Solaris and prevent it from ever threatening the world. However, extinguishing Solaris then would also mean that the events surrounding Sonic's and Elise's friendship would never happen. Reluctantly, Elise blew out the tiny flame and Solaris ceased to be.
Solaris stands as arguably the most powerful being in the entire Sonic the Hedgehog series. Along with possessing several godlike traits, it took the combined might of three super transformed hedgehogs to defeat him, and even then, they could not actually destroy him. As another testament to his enormous strength, Solaris is one of the few beings seen that has been able to injure someone in a Super State through sheer force.
A transcendent life form, Solaris exists in the past, present and future simultaneously, making him omnipresent throughout time and virtually impossible to defeat, unless he is attacked simultaneously in all time periods.
As a god over time, Solaris possesses the ability to freely manipulate and change the fabric of time itself. According to Dr. Eggman, Solaris is capable of devouring time and space on an incomprehensible scale, encompassing entire dimensions and timelines. He can also create time-space rifts which come in two variants: black orbs that can suck objects into oblivion and red orbs that can hurl meteors of condensed matter with such force that they can bypass the invulnerability granted by a Super State.
Solaris possesses unbelievable high physical durability, nearing that of invulnerability, being unaffected by standard attacks from even super transformed characters. Even when unprotected, Solaris's natural durability is so high that so far only super-charged Chaos Powers from super transformed characters can harm him, hinting an immeasurably high level of durability.
Solaris is capable of energy projection, being able to fire energy blasts that are so powerful that they can bypass the invulnerability granted by a Super State. When projecting energy, Solaris can fire it in the shape of both large laser beams and purple orbs that will follow the opponent until it hits. In his second form, Solaris demonstrated the ability to generate an almost impenetrable shield of light that can block any attack and which can only be bypassed when Solaris himself attacks as he has to put it down to launch his own attacks.
Much like his two halves, Iblis and Mephiles, Solaris's physical body appears to be immortal and indestructible, as he easily came back, fully revitalized, after his first defeat by Super Sonic, Super Shadow and Super Silver. His only weak point is his red core that is his consciousness, which is still vulnerable to attacks. By destroying it, it would still leave Solaris' body intact, but he would be unable to use it.
Solaris is also capable of at least limited shapeshifting, allowing him to assume new and stronger physical forms, as seen when he changed the sun-like appendage on his back into wings and became even more powerful.
According to Princess Elise and Eggman, Solaris also possesses pyrokinetic abilities, which is further enforced by his relationship to Iblis, a being of fire.