Luma
A Luma is a space creature which first appears in Super Mario Galaxy. They have a habit of calling Princess Rosalina "mama", possibly because she is their caretaker.
In Mario Kart Wii, they float around Rosalina during and after the race.
In Super Smash Bros. for Wii U/3DS and Super Smash Bros. Ultimate, a Luma will assist Rosalina in combat.