Alien (Mario Party series)
From the Super Mario Wiki
Aliens are a species of green creatures appearing in the Mario Party series. Aliens are first seen in Mario Party 5, where they briefly appear in the minigame, ID UFO. They appear in Mario Party 6, only appearing during the nighttime on the board Castaway Bay. They appear near the location of Bowser and Donkey Kong. Aliens are also seen in the Mario Party 7 board, Neon Heights. They are always portrayed either inside or near their spaceship. Its spaceship has star shaped windows. In Mario Party 7, they can be summoned after landing on specific Happening Space, and they will swap the treasure chests in the course.