The vaquero (Spanish: [baˈkeɾo]; Portuguese: vaqueiro, European Portuguese: [vɐˈkɐjɾu], Brazilian Portuguese: [vaˈkejɾu]) is a horse-mounted livestock herder of a tradition that has its roots in the Iberian Peninsula and extensively developed in Mexico from a methodology brought to Latin America from Spain. The vaquero became the foundation for the North American cowboy, in Northern Mexico, Southwestern United States, and Western Canada.

The cowboys of the Great Basin still use the term "buckaroo", which may be a corruption of vaquero, to describe themselves and their tradition. Many in Llano Estacado and along the southern Rio Grande prefer the term vaquero. While the indigenous and Hispanic communities in the age-old Nuevo México and New Mexico Territory regions use the term caballero, this term is likewise used in the Andes regions of South America. Vaquero heritage remains in the culture of the Californio (California), Neomexicano (New Mexico), and Tejano (Texas), along with Mexico, Central and South America, as well as the Asia-Pacific where there are related traditions.