Tarucus is a butterfly genus in the family Lycaenidae. They are commonly known as blue Pierrots or simply Pierrots. The latter name is often used for the closely related genus Castalius. The delimitation of Castalius versus Tarucus is not yet fully resolved, with some species, such as the dark Pierrot, having been moved between the two genera repeatedly. It may even be that they are eventually regarded as synonymous, and in that case the older name Castalius would supersede Tarucus by the Principle of Priority.