The cellular origin of gliomas remains a topic of controversy in cancer research. Advances in neurobiology, molecular genetics, and functional genomics have ushered new insights through exploiting the development of more sophisticated tools to address this question. Diverse distinct cell populations in the adult brain have been reported to give rise to gliomas, although how these studies relate physiologically to mechanisms of spontaneous tumour formation via accumulation of tumour-initiating mutations within a single cell are less well developed. Recent studies in animal models indicate that the lineage of the tumour-initiating cell may contribute to the biological and genomic phenotype of glioblastoma. These results suggest that the cell of origin may not only serve as a source of diversity for these tumours, but may also provide new avenues for improved diagnostics and therapeutic targeting that may prolong the lives of patients.