Donuts are a planet base. They are donuts coated in pink frosting. They appear in the planet Utopia and shoes.
Donuts can also be found in Angry Birds Seasons, two examples being Level 1-9 of Haunted Hogs and Level 1-12 of Easter Eggs.
They appear in Angry Birds Friends as well, including in the center of Level 6 of Week 191 in the Weekly Tournament.