The Wild Boar is one of the world’s most dangerous invasive species. It is now established in many regions beyond its native range, including many Brazilian states. However, the species has never been recorded from the Brazilian state of Maranhão. Here, we report the first occurrence of this species from Lençóis Maranhenses National Park, within the municipality of Barrerinhas, Maranhão state. We discuss the negative effects of this introduction on native species, including the problem with predation of nests of an endangered turtle species by Wild Boar.