 Protein toxins have evolved to provide defense mechanisms against predation, grazing or enhance pathogenic competence in organisms. Efforts have been made to study their mechanism of action and develop antidotes, while also exploring their pharmaceutical potential for impairing essential cellular processes and damaging target cells. This review summarizes major advances in the field of toxin-based therapeutics and describes the mode of action of each applied toxin. This article was authored by Aitai Benhar and Asav Shapiro.