Jasen is a village in Bosnia and Herzegovina. According to the 1991 census, the village is located in the municipality of Ilidža.
The Public Enterprise for Managing and Protection of the Multipurpose Area Jasen or just Reservе Jasen is a nature reserve in the Republic of Macedonia. It was turned into a protected nature reserve in 2010 (part of it was declared a reserve as far back as 1958) and is situated only 15 km from Skopje. The park compromises around of caves, mountains, underground rivers and lakes. The lowest point is the still uncharted canyon lake Matka. The highest point is Mount Karadzica with a height of almost .
The park is home to the endangered Eurasian lynx and the rare Balkan chamois.
Jasen is both a masculine given name and a surname. Notable people with the name include:
- Jasen Fisher, American actor
- Jasen Mesić, Croatian politician
- Jasen Rauch, American musician
- Hernán Jasen, Argentine basketball player
- Matthew J. Jasen, American lawyer and politician