Bahamut

Bahamut, the platinum dragon also referred to as the God of Dragons or the Lord of the North Wind, is a powerful dragon and the supposed king of the good dragons.

Sages continue to debate whether he actually is a deity or not. According to draconic legend, he has existed since the beginning of time (which, in a dragon's reckoning is since the first dragon appeared on Toril). Whatever he is, he is certainly powerful and venerated by many good dragons and respected by evil ones.

One of the most compassionate beings in Realmspace, his name is known throughout the Forgotten Realms cosmology, Realmspace and in some aspect all over Toril.

Description
Bahamut is depicted as a massive dragon (approx 180 feet (55m) long with a tail the same length as his body) with platinum scales and blue eyes, the exact color of which is hard to specify and may depend on Bahamut's mood.

When he wishes to interact with mortals, he appears as an old man, accompanied by seven gold great wyrms polymorphed into canaries. Some claim these wyrms are reincarnations of dead kings, renowned for their senses of justice.

Combat
Bahamut disdains combat, usually getting goodly adventurers of great power to do his fighting for him. Despite this, he is easily capable of defending himself. Those who have seen him fight claim that he has two breath weapons, one a powerful cone of cold, the other a vapor that turns his enemies into gaseous forms. A third special attack is his roar, which disintegrates creatures or objects within 100 feet (30m). If facing off against more powerful creatures, this roar will still permanently deafen those who aren't turned to dust. On top of that he is a powerful warrior and is also reputed to know every arcane and divine spell.

Tiamat & Bahamut
Bahamut's antithesis is Tiamat, the chromatic dragon and 'Queen of Evil Dragons', worshiped by most evil dragons. Legends of their hatred of each other date back to times before Tiamat is supposed to have arrived on Toril.