Mach O, mach 0, Mach Zero, or, variant, may refer to:
- Mach-O, the Mach object executable file format
- Mach-O Acres Airport (FAA id: 98OR), Sheridan, Yamhill County, Oregon, USA
- Mach 0, a mach number
- M.A.C.H. Zero (IPC Media), fictional character from the comic book 2000 AD