Plasma cell myeloma (PCM) of the skull base is rarely encountered in neurosurgical practice. PCM has a wide spectrum of pathology, including a quite benign, solitary plasmacytoma (SPC), and an extremely malignant, multiple myeloma (MM) at the two ends of the spectrum. We have described two patients with PCM of the skull base, of which one harbored SPC, and the other progressed to MM. In case 1, a 46-year-old man presented with left multiple cranial nerve impairments and had a large skull base tumor. Subtotal removal was performed. The specimen and general examination, including bone marrow aspiration, revealed SPC. Postoperatively 50Gy of external radiotherapy was administered. The patient has no manifestation of MM 24 months after the initial presentation. In case 2, a 53-year-old woman presented with left abducens palsy and had a left petroclival osteolytic mass. Gross total resection was performed. The specimen revealed a plasmablastic tumor, i.e., myeloma. General examination established the diagnosis of MM. She was administrated adjuvant chemotherapy and autologous bone marrow transplantation. She is alive without local recurrence 30 months after the initial presentation.