Astaroth

Astaroth was a demon lord of the Infinite Layers of the Abyss, but ruled no layer of his own. His title was Diabolus and he was concerned with matters of prophecy. After his death, "Astaroth" became an alias for the arch-devil turned god Gargauth. The original became a vestige.

History
Some time in history, Astaroth—then a very powerful demon lord—was killed by Gargauth during his wanderings as an exile of the Nine Hells. Gargauth took Astaroth's name as his alias and stole the worship of his few surviving cultists on Toril, thus receiving his first taste of godhood.

Thereafter, Astaroth was presumed deceased, at least to other fiends. Nevertheless, it was whispered on Toril that the demon lord remained alive but sleeping, within a temple dedicated to him. This account went on to warn that Astaroth still sought to "poison the words" of those who entered imprudently.

In the mid–14 century DR, a cadre of demon-spawned tieflings arose in the former lands of Narfell. Naming themselves the Scions of Astaroth, or "Astarothans", after the long-dead demon lord, they viewed Faerûn as another front in the Blood War.

Circa 1374 DR, an Olin Gisir of the North named Meraera and her party explored the ruins of the temple to Astaroth. Meraera warned her companions to be silent, and claimed to be prepared with just the spells to keep Astaroth in his slumber.

Relations
Helanna Darkstorm, a leader of the Knights of the Shield around 1370 DR, was once a consort of Astaroth.

The False Astaroth
After slaying the demon lord, Gargauth used "Astaroth" as an alias for his misdeeds. For example, in the dwarven legend titled "The Legacy of Astaroth", Gargauth adopted the guise of a dwarf minstrel named Astaroth to corrupt a hall of greedy dwarves and lead them to their doom. Gargauth provided the spell Astaroth's augmentation to priests of other gods who unwisely called upon him.

Background
For a third Astaroth, the "Urban Magic" Web Enhancement for Cityscape presents a fallen angel turned vestige also named Astaroth. However, this Astaroth never became a fiend, had no apparent interest in prophecy, and died at mortal hands, so it is unlikely to be the same entity as the demon lord Astaroth.