ACE2 and COVID-19: This review has covered the clinical COVID-19 manifestations that could be linked to endothelial cell dysfunction, the molecular biology of SARS-CoV-2 entry into ACE2-expressing endothelial cells, immune reactions that are both dictated by and perpetuated upon endothelial cells, current COVID-19 therapies reported to address aspects of endothelial cell biology, and perturbation of canonical and non-canonical endothelial cell biological processes (exosome production and transdifferentiation) by this unique virus.