Head-and-neck necrotizing fasciitis (NF) is a life-threatening medical and surgical emergency that is strongly associated with high mortality. NF of the head and neck occurs only rarely and might mimic abscess or cellulitis. The most common sites for this infection are the pharynx, teeth, or submandibulocervical region. Odontogenic infection is the most frequent cause of head-and-neck NF; other causes, such as peritonsillar abscess, tonsilitis, or salivary gland infections, have been documented. The most prevalent comorbidity of this life-threatening condition is diabetes mellitus. Ideally, it is diagnosed clinically; however, other laboratory and imaging modalities help to support the diagnosis. Furthermore, NF causes serious complications, specifically airway compromise. Overall, surgical intervention is the modality of choice for treating NF. This review article gathers updated data about NF of the head and neck.