Aconitine is an alkaloid toxin produced by various plant species belonging to the genus Aconitum, known also commonly by the names wolfsbane and monkshood. Monkshood is notorious for its toxic properties.

Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar structure may also be termed alkaloids. In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen or sulfur. More rarely still, they may contain elements such as phosphorus, chlorine, and bromine.