PURPOSE Malignant optic glioma of adulthood is a rare, invasive neoplasm of the anterior visual pathway with 66 cases reported in the literature. It presents as anaplastic astrocytoma (WHO grade III) or glioblastoma (WHO grade IV). The present case series covers the spectrum of disease manifestations, discusses neuroradiological findings, and reviews the current literature. METHODS Retrospective case series of five patients from three tertiary referral centers and literature review. RESULTS Visual loss with or without pain was the presenting symptom in all patients (two women, three men). Two patients were initially misdiagnosed as optic neuritis, and one patient as atypical non-arteritic anterior ischemic optic neuropathy (NAION). A neoplastic disease was suspected in the two remaining patients. MRI features were iso- to hypointensity on T1-weighted native images, contrast enhancement, and hyperintensity on T2-weighted images. Biopsy was generally diagnostic; however, one patient required two biopsies for diagnosis. The series includes an exceptional case of intraocular tumor extension and vitreous spread. The disease was lethal within one to two years in all patients. CONCLUSIONS Malignant optic glioma is a diagnostic challenge and remains a devastating and lethal disease. Advances in the understanding of tumor biology have yet failed to translate into effective treatment regimens.