Orthohantavirus is a genus of single-stranded, enveloped, negative-sense RNA viruses in the family Hantaviridae within the order Bunyavirales. Members of this genus may be called orthohantaviruses or simply hantaviruses.

Orthohantaviruses typically cause chronic asymptomatic infection in rodents. Humans may become infected with hantaviruses through contact with rodent urine, saliva, or feces. Some strains cause potentially fatal diseases in humans, such as hantavirus hemorrhagic fever with renal syndrome (HFRS), or hantavirus pulmonary syndrome (HPS), also known as hantavirus cardiopulmonary syndrome (HCPS), while others have not been associated with known human disease (e.g. Prospect Hill virus). HPS (HCPS) is a "rare respiratory illness associated with the inhalation of aerosolized rodent excreta (urine and feces) contaminated by hantavirus particles."

Human infections of hantaviruses have almost entirely been linked to human contact with rodent excrement; however, in 2005 and 2019, human-to-human transmission of the Andes virus was reported in South America.

Orthohantaviruses are named for the Greek word ortho- meaning "straight" or "true" and for the Hantan River in South Korea, where the first member species (Hantaan virus) was identified and isolated in 1976 by Ho Wang Lee.