Germacrenes are a group of five naturally occurring volatile organic hydrocarbons of the sesquiterpene and cycloalkene class. Germacrenes are typically produced in a number of plant species for their antimicrobial and insecticidal properties, though they also play a role as insect pheromones. Two prominent molecules are germacrene A and germacrene D.

Germacrene has five isomers.

The essential oils of deadnettles (genus Lamium), hedgenettles (genus Stachys), and Clausena anisata are characterized by their high contents of germacrene D. Germacrene B is a major component of patchouli oil.