Ztarnoir is the main enemy in Mario & Luigi: Sibling Warfare. He is black with red eyes. It is possible that Ztarnoir was the creator of the Dark Star that appeared in Mario & Luigi: Bowser's Inside Story.
Ztarnoir first appeared in Mario & Luigi: Sibling Warfare. He was originally a member of the Star Sprite clan, but was imprisoned because he wanted more power. In his first form, Ztarnoir looks just like the other Star Sprites, only his face looks a lot like Popple and he is black.