[[File:|thumb|284px]]The Fossas are the main antagonists in Madagascar; they are seen in Madagascar as the main villains, and in Madagascar: The Video Game as supporting villains. They appear as medium-sized weasel-like creatures and rarely speak, instead usually growling and yelping.
Throughout Madagascar, they are shown to terrorize the lemurs and attempt to eat them. According to Julien, "they're always annoying us by trespassing, interrupting our parties, and ripping our limbs off." When they do speak, they put "fossa" in front of every word: ex. "Fossa hungry, fossa eat." They are terrified of Alex due to him being a lion and being much more physically powerful and intimidating. In the end, thanks to a setup performed by his friends and the penguins, Alex made sure that the fossas never bothered the lemurs ever again.