Microglia are resident macrophage-like glial cells located throughout the central nervous system. They play essential roles in maintenance of normal brain function, and act as sentinels through interactions with both neuronal and non-neuronal cells to detect pathology. As a group, microglia can manifest a spectrum of phenotypic profiles determined by various factors, making the standard M1/M2 classification applied to macrophage activation inadequate. This functional heterogeneity is the basis of both the brain-protective and also destructive pro-inflammatory actions perpetuated by microglia. Understanding how these cells are involved in neurodegenerative disease progression, and how they respond to pathogens like coronavirus, are just two of many important avenues of microglial research (1, 2).