The acronym ARENA may refer to either:

• Nationalist Republican Alliance, a political party of El Salvador.
• National Renewal Alliance Party, a former party of Brazil.
• Former name of the Committee for Accuracy in Middle East Reporting in America.
• Action Resource and Education Network of Aotearoa, an anti-globalisation organisation in New Zealand.
• The Australian Cable channel Arena.
• Arena Active Protection System, a Russian Active Protection System.
• The Association for Research on Ethnicity & Nationalism in the Americas.

An arena is an enclosed area, often circular or oval-shaped, designed to showcase theater, musical performances, or sporting events. It is composed of a large open space surrounded on most or all sides by tiered seating for spectators. The key feature of an arena is that the event space is the lowest point, allowing for maximum visibility. Usually, an arena is designed to accommodate a fairly large number of spectators.