Belgabad was the largest and oldest dragon not bonded with a Rider who lived at the time of the Fall of the Dragon Riders. Glaedr called him "the greatest of us all". He was a distant ancestor of Raugmar the Black who was the great-great-great-grandsire of Saphira's mother, Vervada. In Inheritance when Eragon and Saphira visited Doru Areaba on Vroengard, Saphira says that she is proud to be of his blood.
His skull alone was longer and taller than the main part of Saphira's body, while Eragon surmised his ribs to be at least 80 feet long and 15 feet wide at their thickest.
Belgabad died in the Battle at Doru Araeba. After his death, Galbatorix cut a black mantle and a pair of gloves from his wings. Glaedr, Saphira and Eragon found his skeleton in the ruins of Doru Araeba when they visited Vroengard.
Later, when Shruikan flew over the camp of the Varden by Urû'baen, Eragon estimated that Shruikan might be as big or bigger than Belgabad. In Inheritance (book), Galbatorix says "I cut this mantle from the wings of Belgabad himself, and my gloves too" (711), implying that he had either slain Belgabad, or one of The Forsworn had done the deed.