The Lougarou is essentially the Haitian variation of the werewolf legend. Per Mysterious Universe, there are a couple of superstitions surrounding these monsters that have scared the locals throughout the centuries. Some people believe that they are shapeshifting sorcerers who wear animal skins. Conversely, they are also said to be human beings who have been possessed by evil spirits that wield the power to transform their hosts into animals such as wolves, dogs, cats, birds, and reptiles.
"The Winchesters" alters some details regarding the Lougarou. The pilot episode sees Mary and John confront the wolf in Louisiana, which is still quite relevant as the American state has a similar legend. As noted by Pelican State of Mind, the wolf-like creatures are rumored to dwell in the swamplands, albeit with a different name and backstory. Known as Rougarou, the Louisianan wolves supposedly migrated to the state from France in the 16th century, though it's also believed that people would turn into Rougarou creatures if they did not follow the rules of Lent for seven years.
So, why was the Louisana version of the creature named after the Haitian legend on "The Winchesters," you ask? Most likely, the creators wanted to avoid confusion with the humanoid monsters known as the Rugaru that appeared on "Supernatural" back in the day.
