Astrogha was a favoured servant of Diablo as well as his contact on Sanctuary during the Sin War (he is also referred to as a pet). The demon has many incarnations but in the Sin War he is a mix of both arachnid and human, which appears to be his preferred form.
The Sin War
Astrogha inhabits the main Temple of the Triune and acts as Diablo's representative on Sanctuary, possibly placing him second in command of the temple. Though a somewhat reluctant ally of Lucion, son of Mephisto and leader of the Triune, Astrogha makes no move to usurp Lucion so long as the demon retains the favor of the Prime Evils. After Lucion's strange disappearance at the end of Birthright however, Astrogha takes command by disguising himself as Lucion. His plan works until Lilith, sister of Lucion and currently also disguised as her brother, appear. Incorrectly believing Lilith to truly be Lucion, Astrogha at first abandons his plans until he discovers her true identity. After Astrogha finally realized Lilith was now using the guise of the Primus the two have a short showdown with Lilith emerging victorious. Astrogha is not surprised by this, since Lilith is the child of a Prime Evil, and subsequently flees the temple.
Astrogha appears as a giant, humanoid spider. His lower body is that of a spider, but his torso and head resemble something vaguely human, aside from the fact that his shoulders are broader than a normal humans would be. He has eight limbs that end in clawed appendages and on his head he has eight hand-like limbs, used for pushing prey into his mouth. His eyes are described as a cluster of crimson eyes all lacking pupils. Using those eyes he can see in almost every direction and even to other planes of existence. It is suggested that Astrogha can change his appearance and body build at will. 
Astrogha can create various sized spider-spawns made of his essence which he calls 'Children'. They may act as spies or be used to distract or poison an enemy. These spiders appear around him seemingly without him noticing, as even when he is impersonating Lucion they still appear and crawl all over his body.
Similar to any arachnid he has the ability to create thick webbing which he uses to constrict prey in, a web which he may dissolve simply by breathing on it. He then feeds on human bodies, sucking out their fluids.
- Scales of the Serpent, page 73. Richard A. Knaak, 2007.
|Prime Evils||Baal • Diablo • Mephisto|
|Lesser Evils||Andariel • Azmodan • Belial • Duriel|
|Notable Demons||Assur • Astrogha • Gulag • Thonos • Kabraxis • Lilith • Lucion • Xazax • Grimspike|
|Characters in the Diablo novels|
|The Sin War Trilogy||Humans||Uldyssian • Mendeln • Serenthia • Achilios • Lylia • Malic • Rathma • Bul-Kathos|
|Angels||Inarius • Imperius • Auriel • Itherael • Malthael • Tyrael|
|Demons||Lilith • Lucion • Astrogha • Gulag • Mephisto • Diablo|
|Legacy of Blood||Norrec Vizharan • Sadun Tryst • Fautzin • Kara Nightshadow • Hanos Jeronnan • Augustus Malevolyn • Galeona • Meshif • Drognan • Horazon • Xazax|
|The Black Road||Darrik Lang • Buyard Cholik • Kabraxis|
|The Kingdom of Shadow||Kentril Dumon • Quov Tsin • Juris Khan • Zayl • Humbart Wessel • Diablo|
|Moon of the Spider||Zayl • Humbart Wessel • Aldric Jitan • Astrogha • Karybdus|
|Demonsbane||Siggard • Assur • Tyrael|