Underground (Serbian: Подземље / Podzemlje), is a 1995 epic satirical black comedy war film directed by Emir Kusturica, with a screenplay co-written with Dušan Kovačević. It is also known by the subtitle Once Upon a Time There Was One Country (Serbian: Била једном једна земља / Bila jednom jedna zemlja), the title of the five-hour miniseries (the long cut) shown on Serbian RTS television.

The film uses the epic story of two friends to portray a Yugoslav history from the beginning of World War II until the beginning of the Yugoslav Wars. It is an international co-production with companies from Yugoslavia (Serbia), France, Germany, Czech Republic and Hungary. The theatrical version is 163 minutes long. Kusturica stated in interviews that his original version ran for over five hours, and that co-producers forced edits.

Underground received critical acclaim, and won the Palme d'Or at the 1995 Cannes Film Festival. It was Kusturica's second win following When Father Was Away on Business (1985). It went on to win other honours.