@Delightfully Smoak they're forest spirits that inhabit the kokiri/great hyrule forest in Legend of Zelda. They first appeared as Kokiri (in the form of never aging kids similar to the lost boys a la Peter pan). This was mainly so that the protagonist, who was a Hylian, didn't feel alone. They next appeared in Wind Waker in their true forms, like tiny walking plants/trees with leaf masks (as tall as about knee to mid thigh height). They are also present in Breath of the Wild, although in a far more annoying and greater capacity (there are 900 hidden throughout the entire continent to find, although it is optional, I just have nothing else to do until the downloadable content arrives)