The human complement system is represents the main effector arm of innate immunity and its ambivalent function in cancer has been subject of ongoing dispute. Glioma stem-like cells (GSC) residing in specific niches within glioblastomas (GBM) are capable of self-renewal and tumor proliferation. Recent data are indicative of the influence of the complement system on the maintenance of these cells. It appears that the role of the complement system in glial tumorigenesis, particularly its influence on GSC niches and GSC maintenance, is significant and warrants further exploration for therapeutic interventions.