Catachan Barking Toad
The Great Barking Toad (Catachanus bufo moribundus) of the Death World of Catachan is considered the most poisonous creature in the entire galaxy; fortunately, it is extremely rare. When threatened, it emits a cloud of toxins that kills all life within a kilometer, including the Barking Toad itself. The poison is so virulent it can penetrate even power armour.
The Lesser Catachan Barking Toad is the smaller cousin to the Great Barking Toad and is far less destructive, killing anything only within the immediate area.