Gliomas, much like other cancers, are composed of a heterogeneous mix of neoplastic and non-neoplastic cells that include both native and recruited cells. There is extensive diversity among the tumor cells, with differing capacity for in vitro and in vivo growth, a property intimately linked to the cell’s differentiation status. Those cells that are undifferentiated, self-renewing, with the capacity for developing tumors (tumorigenic) cells are designated by some as cancer stem cells, because of the stem-like properties. These cells may be a critical therapeutic target. However the exact identity and cell(s) of origin of the so-called glioma cancer stem cell remain elusive. Here we review the current understanding of glioma cancer stem cell biology.