Z3 may refer to:

• Z3 (computer), a computer created by Konrad Zuse
• AEG Z.3, a German aircraft built before World War I
• BMW Z3, a BMW sports car model
• Motorola Z3, a telephone
• BlackBerry Z3, a smartphone
• Sony Xperia Z3, a smartphone
• , a television series
• Z3 file extension, a story file for the Infocom Z-machine
• [https://github.com/Z3Prover/z3/wiki Z3 Theorem Prover], an SMT Solver by Microsoft

The Z-machine is a virtual machine that was developed by Joel Berez and Marc Blank in 1979 and used by Infocom for its text adventure games. Infocom compiled game code to files containing Z-machine instructions (called story files, or Z-code files), and could therefore port all its text adventures to a new platform simply by writing a Z-machine implementation for that platform. With the large number of incompatible home computer systems in use at the time, this was an important advantage over using native code or developing a compiler for each system.