The Great Dragon is the creator of the Magic Dimension.Its magic is called the Dragon Flame, which is also the source of Bloom's powers. Its power is the absolute opposite to that of the Shadow Phoenix, Lord Darkar , (the Shadow Fire in the 4Kids continuity), who was created together with the Dragon at the Beginning of Time and whose power is to absorb energy while the Dragon creates it, and the elemental opposite to that of the Water Stars, them only having the power to extinguish the Dragon's Flame as both the Dragon and the Water Stars produce energy which are of opposite nature.
The Great Dragon has the appearance of a Chinese Dragon made entirely of fire with only two forelimbs.
According to Miss Faragonda, the Great Dragon was born at the beginning of Time from the dark Void as a dazzling light and created the whole of the Magic Dimension with its fiery breath, where it spread life, light and heat.
Later it became exhausted and chose as resting place the planet Domino, and since then the royal heirs of the royal family of Domino have been the Guardians of the Dragon Fire, the present Guardian being Bloom.In the first season, when Bloom does research in the library at Alfea, she finds in the books there that after the Dragon disappeared, the Magic Dimension was consecutively ruled by the nine Nymphs of Magix, all-powerful fairies who had controlled the destiny of the Magic Dimension and had been the previous Guardians of the Dragon's Fire (possibly implying that they were her ancestors), the last being Daphne, (Bloom's own elder sister, even if she did not know it then).
When Darkar tried to gain control of the Ultimate power, he sent his servers, the Ancestral Witches and Valtor, to claim the Dragon Fire from Domino, therefore causing the planet's destruction. When all the inhabitants of Domino disappeared in the final battle between the Company of Light and the Ancestral Witches, the whole Magic Dimension thought that the Dragon's Flame had been extinguished, until the Trix stole it from Bloom and revealed to her that it was still burning in her, since she was its Guardian. This was confirmed when Bloom openly used the Dragon's Flame in the final battle against the Trix.
In the third season, it is revealed that when the Great Dragon created the Universe, a small part of its Fire mixed with the Darkness, creating a kind of Dark Dragon's Fire which the Ancestral Witches found and fashioned into a man they raised as if he were their own son and named him Valtor.
It is possible that the part of Darkness which mixed with the Dragon Fire from which Valtor was created was in fact a small piece of Darkar's darkness, since it was stated that both the Shadow Phoenix (Lord Darkar) and the Great Dragon both were born in the original Void before the beginning of Time, which possibly means that they were born together at the same time, since in the first episode of the second season, Proffessor Wizgiz said, that in the Magic Dimension everything and every magic power has an opposite, also implying that opposite powers are created together.