Activator may mean:
- Activator (genetics), a DNA-binding protein that regulates one or more genes by increasing the rate of transcription
- Activator (proteomics), a type of effector that increases the rate of enzyme mediated reactions
- Sega Activator, a motion-sensing controller for the Sega Genesis
- Activator technique, a method of spinal adjustment
- Activator, a hardcore band from Brooklyn Ny.