Covering: up to 2019The reactions catalysed by terpene synthases belong to the most complex and fascinating cascade-type transformations in Nature. Although many accept only one natural terpene precursor and convert it with high selectivity into only one product, several of these remarkable biocatalysts were recently shown to have a surprising plasticity towards non-natural substrate analogues. For an easy access to the topic also for readers who are new to the field, this review will first briefly cover the principles of natural terpene biosynthesis. This is followed by a chapter that highlights purely chemical transformations mimicking terpene synthase catalysed reactions. Then, the main focus of this article will shed light on the recent advances of terpene synthase catalysed transformations of synthetic substrate analogues. As will be demonstrated, a simple conceptual approach extensively broadens the chemical space that can be reached with terpene synthases.