Toxins types can be very varied. From proteins, small molecules or peptides they are all biologically produced. For example the botulism toxin is a protein produced by the bacteria butulinum and is very toxic to humans one of the most powerful neurotoxins.
Toxins perform important roles in the animal kingdom in both predation and defence. For example spiders and snakes use specifically produced poisons for capturing prey, while bees and wasps use toxins for deterring predators.