Dark Sky (ダック ・スカイ Dakku Sukai) is a transformation of Sky the Hedgehog. Sky only takes this form when she gets extremely mad.
In this form, Sky's fur turns a deathly black and her eyes are glowing a dark purple.
Unlike her other forms, this form requires Sky's anger to active. When in this form, Sky's powers are greatly enhanced.
This form has yet to appear.