Neuro-ophthalmic emergencies can cause life-threatening or sight-threatening complications. Various conditions may have acute neuro-ophthalmic manifestations, including inflammatory or ischemic processes, as well as tumoral, aneurysmal compression or metabolic and systemic diseases. Diplopia related to a partial third nerve palsy with pupillary involvement may reveal an intracranial aneurysm. Abnormalities of conjugate gaze may reveal an inflammatory or ischemic lesion, most often of the brainstem. An intracranial tumor may also manifest itself as a single or multiple oculomotor palsy, or causing various visual field defects, due to optic nerve, chiasm or retrochiasmal involvement. Arteritic anterior ischemic optic neuropathy may be the first manifestation of giant cell arteritis, prompting rapid treatment with steroids to prevent contralateral involvement. A (painful) Horner syndrome may be the presenting sign of carotid dissection, or it may be a sign of a central or thoracic sympathetic lesion. Beyond these classical emergencies, this non-exhaustive review will also present more rare clinical situations, describing novel algorithms for quick recognition and prompt intervention in acute neuro-ophthalmology.