Covering: up to July 2020Fungal meroterpenoid cyclases are a recently discovered emerging family of membrane-integrated, non-canonical terpene cyclases. They catalyze the conversion of hybrid isoprenic precursors towards complex scaffolds and are therefore of great importance in the structure diversification in meroterpenoid biosynthesis. The products of these pathways exhibit intriguing molecular scaffolds and highly potent bioactivities, making them privileged structures from Nature and attractive candidates for drug development or industrial applications. This review will provide a comprehensive and comparative view on fungal meroterpenoid cyclases, their intriguing chemistries and importance for the scaffold formation step towards polycyclic meroterpenoid natural products.