Flying Blue Elves are small creatures found in the original Rayman game, more precisely in Band Land and Picture City. They have the ability to shrink Rayman down to a minuscule size by touching him. This allows him to enter small passages that were inaccessible at his normal size. Touching them again causes Rayman to return to his original size. Rayman's ability to resize himself is revisited in Rayman Revolution by eating a Yellow mushroom in a hidden area of the Fairy's Glade. In Rayman Origins this ability became available as a power, obtainable by saving Edith Up, the nymph of the Gourmand Land. However the blue elves are replaced by funnels in this game, though both bear strong resemblance in eyes and wings.

Rayman was shrunk down by this Flying Blue Elf
These little creatures give Rayman the ability to shrink down in size, so he can pass easily through some of the game’s narrow passages. Walk up to one to become small, and walk back up to him or to another one to become normal-sized again.
—Manual, Rayman