From Lexicanum

A δτ-class² or death world is a planet in which the native flora and fauna has evolved into naturally aggressive and dangerous forms. These eco-systems are finely balanced between continual destruction and lightning-fast reproduction. Death worlds take many forms, ranging from jungle-covered hell-holes with carnivorous plants and animals to barren, volcanic wastelands racked by ion storms.

Humans can, and do, live on these worlds, but it is a never-ending struggle. On many death worlds it is as if the entire bio-mass of the planet were consciously motivated against human settlement - concentrating forces against intruders to destroy them.¹ Death worlds with human settlements or colonies can have populations of 1,000 to 15,000,000²

Death worlds are not usually inhabited, and are nearly impossible to colonise but still need to be explored which means establishing outposts and other facilities. Some planets have rich mineral wealth, animal life, vegetables or gases, so tithes might range from Solutio Tertius to Solutio Prima².

Notable Death Worlds

• Caliban (destroyed)
• Catachan
• Cthelle
• Cretacia
• Hyperion
• Kanak
• Krieg
• Lost Hope
• Luther McIntyre IX
• Miral
• Nocturne
• Piscina V

Sources

• ¹:Warhammer 40,000: Rogue Trader p. 134
• ²:Warhammer 40,000 3rd Edition Rulebook p. 115

Worlds of the Galaxy

Imperium	Adeptus Astartes Homeworld • Agri World • Cardinal World • Civilised World • Dead World • Death World • Desert World • Feral World • Feudal World • Forge World • Hive World • Ice World • Industrial World • Jungle World • Knight World • Mining World • Ocean World • Paradise World • Penal World • Research Station • Shrine World
Xeno	Xenos World • Daemon World • Exodite World • Tomb World • Maiden World • Crone World • Ork World • Tau Empire • Craftworld