In the central nervous system, NG2-glia are the cells responsible for the generation of mature oligodendrocytes during development and adulthood. Some studies could show that NG2-glia can give origin also to astrocytes and neurons, a property that makes them similar to neural stem cells. Beside their important role as progenitors, NG2-glia are believed also to have more functions due to their unique interaction with neurons through synapses. It is however not clear whether these features are common to all NG2-glia or different subpopulations of NG2-glia devoted to different functions exist. Therefore the aim of this review is to highlight the state of the art on NG2-glia heterogeneity from development to adulthood and in different brain areas, and discuss the impact of it on our understanding of the glial neurobiology. This article is part of a Special Issue entitled SI:NG2-glia(Invited only).