The Celestial Toymaker, also known as the Crystal Guardian, the Mandarin, or simply the Toymaker, was a powerful being who ensnared sentient beings in apparently childish games, with their freedom as the stakes. However, the Toymaker hated to lose and the games were always rigged in his favour.
Nature and powers
Within his realm, the Celestial Toyroom, the Toymaker commanded immense powers, but they were limited by the rules he set for any particular game, although he could bend these rules or "forget" to mention them to his opponents if he so chose. He himself was immortal and invulnerable, and appeared capable of space and time travel at will.
During the course of a game, one of the players might die outright or they might lose, in which case, the Toymaker would have total control over their life and personality, perpetually. (TV: The Celestial Toymaker) Apart from these children's games, the Toymaker sometimes played in person against his "guests", most often games of chance such as cards or dice. There is evidence to suggest that if he was fairly beaten in such a game, the other player was allowed to go free, but if his opponent lost or tried to cheat, they became another exhibit in the Toyroom. Such opponents included Gaylord Lefevre, a professional gambler from the American west, and a Roman soldier — though it is unclear if the latter played fairly and thus gained his freedom. (COMIC: The Greatest Gamble)
However, by some accounts, the Toymaker feared the outer-universe so badly that he feared the very idea of being forced to leave his toyroom. In this account, the Twelfth Doctor helped create a new one for him, leaving him drifting through time and space. (COMIC: Relative Dimensions)
Some accounts claimed that the Toymaker was one of the Elder Gods, entities from an older universe who had escaped into the Doctor's universe and become godlike there. (AUDIO: Black and White) Indeed, According to the Sixth Doctor, he originated in another universe before this one and was hauled into the Doctor's universe by some kind of catastrophe. Because of this, the usual laws of physics didn't apply to him. The Toymaker himself stated that, while he had used his powers for other things in the beginnings of the universe, he eventually got bored of thousands of millennia of pointless creation and pointless destruction, and found a new source of amusement — games. (AUDIO: The Nightmare Fair) In contrast, the First Doctor believed the Toymaker to be native to the same universe as himself. (PROSE: The Celestial Toymaker)
In yet other accounts, the Toymaker once claimed to be an embodiment of one of the fundamental forces of the universe, much like the Guardians of Time. Whereas the White and Black Guardians personified the absolutes of morality, however, the Toymaker was the avatar of games and illusions, known as the Crystal Guardian. (PROSE: The Quantum Archangel) Along with his fellow Guardians of Time, the Crystal Guardian was in attendance for the creation of the universe. (PROSE: The Whoniverse) According to another account, however, the First Doctor described the Toymaker as having "only" lasted for "thousands of years" when he faced him with Dodo and Steven. (PROSE: The Celestial Toymaker)
Creating the Celestial Toyroom
According to the First Doctor, the Toymaker succeeded in creating a universe of his own, "entirely in his own vision", where he would "manipulate people and turn them into his playthings": the Celestial Toyroom. The Toymaker and his games became "notorious throughout the universe" as he spread his influence to attract people into his world and try to make them part of it. (PROSE: The Celestial Toymaker)
First encounter with the Doctor
According to one source, the Doctor learned of the Toymaker when he was a youth at the Prydonian Academy. The Time Lords' data banks described him only as a vague legend. Indeed, some of the reports in the Time Lords' data banks claimed there may exist several Toymakers rather than just one. The Doctor and his friends Rallon and Millennia who, like the Doctor, belonged to a clique known as the Deca, investigated the legend, travelling to the Toyroom in a stolen TARDIS.
There, they were able to confirm that the Toymaker was a singular being rather than a species. They found him in a dormant, disembodied state, but on their arrival he possessed Rallon and made Millennia one of his living toys. The Doctor defeated him, and the Toymaker allowed him to leave, knowing that he would become an even more worthy opponent given time to mature. (PROSE: Divided Loyalties)
During the latter days of his first incarnation, the Toymaker drew the Doctor's TARDIS back to his realm and made the Doctor and his companions play his games again. This time the Toymaker arranged things so that even if they won, the Toyroom would vanish completely at their moment of victory, leaving him the only survivor and the Doctor and his companions his subjects forever. The Doctor outwitted the Toymaker again and escaped, leaving his realm in chaos. (TV: The Celestial Toymaker) Rallon had been keeping the Toymaker's powers in check since he was first possessed. He made the Toymaker abide by the rules of his games to allow the Doctor to escape. (PROSE: Divided Loyalties) At the end of this adventure, the Doctor believed, incorrectly, that since he had won, the Toyroom no longer existed. (TV: The Celestial Toymaker)
Rebuilding the Toyroom
According to one source, the Toymaker was so terrified of the universe outside of his Toyroom that he refused to allow himself to leave it.
When the Toyroom became old and began to break down, the Toymaker feared that its contents would break out into the universe. He trapped the Twelfth Doctor and Clara Oswald inside, wanting to steal the Doctor's TARDIS in order to keep the Toyroom contained. The Doctor allowed him to take the TARDIS, then made his way into the console room and ejected the Toyroom. The Toymaker was then left with a contained Toyroom once more, "A lonely god, drifting through time and space in his magical toy box." (COMIC: Relative Dimensions)
Leaving the Toyroom
The Toymaker discovered that after centuries of existence, Rallon's body was dying. He set out to ensnare the Doctor again and hatched a complex plot to turn his companions against him and absorb the Doctor as a new host. He was thwarted when Rallon forced himself to undergo multiple regenerations consecutively. The trauma expelled the Toymaker from his body. A projection of Rallon's potential future self merged with the Toymaker to ensure that the full powers of the immortal continued to be kept under control. While waiting for his Toyroom to repair itself, the Toymaker decided to take his servant Stefan to Earth to seek amusement. After seeing the idea in Tegan Jovanka's mind, he decided to take him to Blackpool. (PROSE: Divided Loyalties)
The Toymaker, now calling himself the Mandarin, appeared in Blackpool using a thrill ride, Space Mountain, as his base of operations, and manufactured deadly video arcade games. He was stopped by the Sixth Doctor and placed in an impenetrable force field. Because the Mandarin's mental energy maintained the force field, the Doctor had set it up so that he could never escape it. (AUDIO: The Nightmare Fair)
Still calling himself the Mandarin, he escaped and played chess against Fenric during the latter's imprisonment. The Mandarin found himself on the verge of being outplayed, but slowly realised that, in this case, playing for a stalemate would be a victory of sorts. (PROSE: Games)
Battles with the Eighth Doctor
The Toymaker trapped the Eighth Doctor in a replica of the village of Stockbridge. Here he forced the Doctor to play games for control of a reality-warping alien device called the Imagineum. The Toymaker's pawn this time was a replica of the Doctor himself. The Doctor persuaded his double to turn against his master. With the Toymaker distracted, the Doctor used the Imagineum to create a replica Toymaker, which he set against the original. A stalemate ensued. The Doctor destroyed the Imagineum and freed Stockbridge from the Toyroom. The Toymaker was trapped in apparently perpetual battle with himself. (COMIC: Endgame)
The Toymaker later captured the Doctor's TARDIS and took it to his Toyshop. He transformed the Eighth Doctor into a puppet. The Doctor's companion, Charley, was forced by the Toymaker to take part in his riddle, but was tricked by the Toyshop which shrunk to 0% of its original size and the body he was using was destroyed within it. The Toymaker swore that when his new body had formed he would take his revenge upon the Doctor and Charley, who had escaped the Toyshop's destruction. (AUDIO: Solitaire)
The Seventh Doctor's trap
The Toymaker somehow regained full control of his powers and lured several people into his domain, including the Seventh Doctor and his companions Ace and Hex. Working under the Doctor's leadership, the group of victims were successful in defeating the Toymaker and imprisoning his essence in a doll (or so it seemed). Each of them ate a piece of the doll, dividing the Toymaker so that he would no longer be capable of using his powers. The Doctor concocted an elaborate plan to keep control over the fragments of the Toymaker in the minds of each member of the group until the Toymaker withered away forever. As this plan involved the Doctor forgetting having made the plan in the first place, he wound up short-circuiting it. In the end, it was revealed that the Toymaker had been in control all along, allowing himself to be absorbed into humanity so that he could "feel what it was like to lose". Finally, one of the people involved, the chessmaster Swapnil Khan, managed to trap the Toymaker in a perpetual stalemate in his own dimension, but not before the Toymaker had reduced everyone except the Doctor, Ace, Hex, and Khan's daughter Queenie Glasscock to wooden dolls. (AUDIO: The Magic Mousetrap)
The Toymaker was a tall and imposing man with deep set, glittering eyes. He dressed as a Chinese mandarin, wearing a round black hat with gold thread and a silver, red and blue collar over a dragon-patterned black robe encrusted with rubies, emeralds, diamonds and pearls. (PROSE: The Celestial Toymaker)
Behind the scenes
According to Donald Tosh, (BBC DVD: The Time Meddler) the commissioning script editor and (uncredited) co-author of The Celestial Toymaker, the intention was that the Toymaker was, like the Monk who had predated him, a member of the Doctor's own race.
In the novelisation of The Celestial Toymaker, which was based in part on concepts for the original TV story which had to be abandoned due to a rushed production, the Doctor describes the Celestial Toymaker as native to the universe and several thousands of years old. Additionally, the Toymaker wields a sapphire ring which he uses when altering elements of his realm, such as shrinking toys to human size or making a wall vanish; this is reminiscent of the Doctor's signet ring.
However, this fact has not explicitly been followed upon in any narratives featuring the Toymaker to this day, with other accounts instead positing the Toymaker was something quite different from a Time Lord. Notably, however, the audio story Faustian described the Time Lords as "a celestial race".