Yikk is a character from Mario & Luigi: Bowser's Inside Story. When Bowser enters the Tower of Yikk, and reads through a book he finds on a desk, Bowser's way out is blocked, and Yikk appears from the book as his undead form. Yikk claims he invented the Tower of Yikk and the Boo-Ray Machine. He created the Boo-ray Machine to study Boos and other spiritual beings. After Yikk explains his machine and how to use it, he shuts the book, and goes back into slumber.