Giant vampire bat
Reports of giant vampire bats have occasionally appeared, mainly in northern Argentina and southern Brazil. Giant vampire bats did actually exist in the area, called Desmodeus draculae, but are considered to have gone extinct in the early Holocene, about 10,000 years ago.
The most well-known sighting was published in a newspaper on January 6th, 1969. The article reported that a vampire bat 10 times the normal size was terrorizing various farmers by sucking their livestock's blood in La Quebrada de Hamahuca, a mountainous valley in the Jujuy province near the Bolivian border. The giant vampire bat was eventually killed by a cowherd named Meliton Juárez after it tried to drink blood from the throat of one of his mules. It was well outside the accepted size limits vampire bats are thought to reach, which typically weigh 33 grams or 0.7 pounds, but this specimen weighed 12.1 pounds. Some cryptozoologists, like Angel Morant Forés considers this story to be dubious, due to various locations in the article being misspelled, and a lack of any sources or photos being shown.
The only physical evidence of giant vampire bats surviving more recently was in August of 2000, when paleontologists Ulises Pardiñas and Eduardo Tonni discovered an upper left canine of a D. draculae in an owl pellet in Centinela Del Mar cave, located in Miramar, Argentina. It was dated to be from between the 16th and 18th centuries. D. Draculae could be the source of many Indigenous legends of giant bats or “bat demons."