||This article is about the Hive World; for the Iron Warrior, see Skintaker Algol.
Algol is a Hive World of strategic importance, as it belongs to a trade-chain of densely populated Imperial planets.
Algol found itself assaulted by a Tyranid invasion, and despite having a sizable standing army, the local planetary forces did nothing but provide meat for the alien attackers. Protectorship over the strategically important planet fell to the Ultramarines Chapter, and so the entire Second Company of the Ultramarines, commanded by Captain Severus, committed to cleansing the invasion and also called in the Third Company for aid. But whether the world was devoured or saved from the Tyranids is unknown.