The horizontally transmitted fungal endophytes cause symptomless infections of plants. Endophytes synthesize a diverse array of metabolites and enzymes, an attribute that reflects their milieu: the host plant and co-occurring microbes. We illustrate the versatility and utility of endophytes by highlighting examples of how they enhance plant tolerance to abiotic/biotic stressors, produce biomolecules with unique molecular architectures, and elaborate novel enzymes of industrial importance. After considering the challenges that have retarded the translation of these findings to payoffs, we suggest future directions, including the need to understand the ecology and in planta community structure of endophytes, to help fully realize their technological potential.