Yerba mate or yerba-maté (Ilex paraguariensis; from Spanish [ˈʝeɾβa ˈmate]; Portuguese: erva-mate, Portuguese pronunciation: [ˈɛɾvɐ ˈmatɨ] or [ˈɛʁvɐ ˈmatʃi]; Guarani: ka'a, IPA: [kaʔa]) is a plant species of the holly genus Ilex native to South America. It was named by the French botanist Augustin Saint-Hilaire. The leaves of the plant can be steeped in hot water to make a beverage known as mate. Brewed cold, it is used to make tereré. Both the plant and the beverage contain caffeine.

The indigenous Guaraní and some Tupí communities (whose territory covered present-day Paraguay) first cultivated and consumed yerba mate prior to European colonization of the Americas. Its consumption was exclusive to the natives of only two regions of the territory that today is Paraguay, more specifically the departments of Amambay and Alto Paraná. After the Jesuits discovered its commercialization potential, yerba mate became widespread throughout the province and even elsewhere in the Spanish Crown.

Mate is traditionally consumed in central and southern regions of South America, primarily in Paraguay, as well as in Argentina, Uruguay, Southern Brazil, the Gran Chaco of Bolivia, and southern Chile. It has also become popular in the Druze and Alawite community in the Levant, especially in Syria and Lebanon, where it is imported from Paraguay and Argentina, thanks to 19th-century Syrian immigrants to Argentina. Yerba mate can now be found worldwide in various energy drinks as well as being sold as a bottled or canned iced tea.