Kossolax, also known as Kossolax the Foresworn, is an infamous Chaos Lord who supported Abaddon the Despoiler's 13th Black Crusade and leads a large warband of Khornate Berserkers known as the Foresworn, drawn from the ranks of the sundered World Eaters Traitor Legion. One particular Chaos Rhino, belonging to the World Eaters Legion, was reportedly present at the Battle of Terra during the Siege of the Imperial Palace, and has been identified on numerous occasions over the millennia since as being the vehicle of Kossolax the Foresworn. The vehicle, identified as Barbarus by its nameplate, is covered in iron spikes, each adorned with the severed head of an Imperial warrior. The records of the Ordo Malleus state that Barbarus belonged to the squad of Sergeant Solax of the World Eaters' 3rd Assault Company before the Horus Heresy, and this individual is thought to be the beast now known as Kossolax the Foresworn. If this is indeed the case, Sergeant Solax has risen to the command of an entire company of Khornate Berserkers in the form of the Foresworn, and Barbarus has served with him and his warband across 10,000 standard years.
- Codex: Eye of Terror (3rd Edition), pp. 16, 25
- White Dwarf 286 (UK), "Index Astartes: The Eye of the Storm - Blood Angels," pp.68-69
- White Dwarf 275 (UK), "Index Astartes: Beasts of Steel - Chaos Space Marines tanks - The Rhino"
- Conquest of Armageddon (Novel) by Jonathan Green