This chapter uses a case-based approach to describe a few common seizure mimics that may be mistaken for epileptic seizures in critically ill patients. These include tremors, myoclonus, syncope, and functional seizures (psychogenic non-epileptic seizures). Tremors appear as rhythmic or periodic activity but may be differentiated from seizures by the lack of a definite field and stereotyped pattern without evolution. Myoclonus refers to body or limb jerking movements that may be confused with seizures. Myoclonus may be of cortical or subcortical origin. Cortical myoclonus is associated with time-locked epileptic discharges, whereas subcortical myoclonus lacks an epileptic correlate though myogenic artifact may be seen. Convulsive syncope and non-epileptic psychogenic seizures are also described along with their electrographic patterns.