The Hole-in-the-Wall is a literal hole in the Pun Garden wall, native to the Isle of Wonder. Alexander can look through him and see into Chessboard Land. He is extremely shy, and will run behind some wallflowers if Alexander tries to pick him up. To reach him Alexander must distract the wallflowers by playing a song on a flute.
Once the Hole-in-the-Wall has been obtained, Alexander can use him on the side of the Castle of the Crown on the Isle of the Crown to see into the castle's basement. This is not necessary, however.