The Fossas are the main antagonists of DreamWorks' 10th full-length feature film Madagascar, and major antagonists of the spinoff TV series All Hail King Julien.
They were all voiced by Fred Tatasciore (who also voiced Teetsi in the second film), Tom McGrath (who served as one of the directors of the film, the latter also being the voice of Skipper), and Eric Darnell.
Despite being the main antagonists, their role in the film is small. The fossas first appeared when they crashed King Julien's party and attempted to eat Mort, but when Alex noticed a spider on his back, he lets out a loud scream, causing the fossas to think he is roaring at them and retreat in terror.
The next morning, during Julien's party with Alex and his friends, the fossas came back to eat the lemurs, but Alex roars loudly, causing the fossas to flee.
The fossas made a short appearance during the "What a Wonderful World" scene, where they watched Alex walk through their territory after his predatory instincts forced him to attack his friends.
Then, when Marty convinced Alex to go on the ship with them, the fossas appeared once again and attacked Marty, Melman, and Gloria. Private and his fellow penguins came to the three animals aid, and Alex showed up and clobbered the fossas and scared them away once again. After that, the fossas never bothered the lemurs, Alex, and his friends anymore.
Like any predatory and carnivorous animal in real life that includes their real-life counterparts, fossas love to hunt animals as food. The reason why they proved villainous in the film was due to them being more obsessed in hunting lemurs than any other potential preys available and are indifferent with the fact that focusing their hunt for lemurs would make them go extinct.
Early models of the Fossas.
The Fossas trapping Mort in a salad bowl.
The Fossas stepping aside for the wild Alex.
The Fossas knocked out by the penguins.
The Fossas at the mercy of Alex.
Alex fighting the Fossas.
Alex lifting his friends in front of the Fossas.
The Fossas' defeat.
The Fossas as they appear in All Hail King Julien.
A Fossa as it appears in the GameCube and PS2 versions.
The Fossas as they appear in the GBA and DS versions.
Despite being the main antagonists, they only had around 5 minutes of screen-time.
Unlike their appearance in the film, in real-life, fossas hunts alone instead of hunting in packs.
They are misspelled as "Foosa" in the movie, Netflix original, and video game.
In the video game, they never have any speaking lines and are portrayed as more territorial and formidable than their movie counterparts.
They apparently have their own sovereign called King Fossa in the videogame, who does not appear in the movie at all. He serves as the final boss and as a playable character in the shuffleboard minigame. He also serves as a minor character in All Hail King Julien.
They are commonly mistaken as canines or felines, but they are actually related to mongooses.
The Fossas did not make an appearance near the beginning of their respective film until the second half. This was most likely a way to surprise the audience that they are the main antagonists and not Nana.