Io in the fourth edition core pantheon was the creator of the dragon race.

Not long after creating dragonkind, Io was slain by the primordial Erek-Hus, split from head to tail with a rough-hewn axe of adamantine. By some accounts, Io's death released his divine energies and elevated his two eldest children, Bahamut and Tiamat, to deities,[DCD:26] but by other accounts, Bahamut and Tiamat arose from the two halves of Io's corpse.[DCD:6]

Io was once the chief deity worshiped by dragons, god of all dragonkind, peace and balance. He was seen by his people as creator of all things. He was neutral in alignment, but contained within him all alignments. His symbol was a multi-coloured disk.