Jast may refer to:

• Joint Advanced Strike Technology (JAST) project was merged with the Common Affordable Lightweight Fighter (CALF) project to make the Joint Strike Fighter program.

• JAST USA

• Jast, a member of the Cult of Skaro in Doctor Who.

• JAST, a Japanese game company known for Tenshitachi no Gogo.

• JAST, Journal of Adhesion Science and Technology.