Ophthalmoplegia and blindness caused by squamous cell carcinoma were reported in a cat. Unilateral functional deficits of cranial nerves II, III, IV, and VI and of the sympathetic nerve supply caused blindness, complete ophthalmoplegia, and Horner syndrome. Radiography and computed tomography revealed a proliferating bony lesion associated with the right tympanic bulla, right temporal bone, right side of the mandible, and left frontal bone. A focal area of bony destruction involved the right sphenoid bone. The cat was euthanatized and necropsied. Squamous cell carcinoma was identified invading the bones and rostral part of the right side of the skull. The tumor had extended through the sphenoid bones into the region of the cavernous sinus and had surrounded the cranial nerves passing through this region. It also had invested connective tissue surrounding the optic nerves and had invaded the right globe through the lamina cribrosa. This represents an unusual distribution for ocular cranial squamous cell carcinoma in a cat.