Peso is the name of the currency of various countries:

• Argentina: Argentine peso (ISO 4217: ARS)
• Chile: Chilean peso (CLP)
• Colombia: Colombian peso (COP)
• Cuba: Cuban peso (CUP)
• Dominican Republic: Dominican peso (DOP)
• Mexico: Mexican peso (MXN, previously MXP)
• Philippines: Philippine peso (PHP)
• Uruguay: Uruguayan peso (UYU)

In Spanish "peso" means weight. Spanish is – or was, in the case of the Philippines – spoken in all these countries. The main Spanish coin of colonial times was a piece worth eight reales. This is the famous "piece of eight" and later became called the peso. The peso coin weighed 27 grams and was of 92 per cent pure silver. It was the template for the coins of the United States and one silver dollar equaled exactly one peso.

Spanish pesos circulated throughout the European colonies in the Americas. They were also later used in the independent United States, where they continued to be legal tender until they were demonetized in 1857.

Bolivia traded in its Bolivian peso for its new currency, the boliviano (at a ratio of one million to one), in 1990.

Portuguese-speaking Guinea-Bissau previously used pesos (GWP) prior to adopting the CFA franc (XOF) upon accession to the West African Economic and Monetary Union (UEMOA) on 1 May 1997.