The Book of Skylanders is a relic in the Skylanders Academy television series that contains every Skylander ever documented. When a Skylander is drawn into the book, they are bound into its pages as whoever has the book controls the Skylanders' actions, and their state of being. While Master Eon draws in the Skylanders, Hugo adds in the finishing details.
Previously to the start of the series, the Book was secured in the Academy's Relics Room, protected by a magical pad that would shock whoever touched the book hovering above it, activated by a lever. At the end of the Skylander Games, Eon would retrieve the book from the vault to draw the newest Skylanders for the end of the graduation cerimony.
In the series' debut, Kaos was able to steal the book and use his magic to freeze it, thus freezing all the Skylanders who were recorded in the book. After Spyro defrosted the Book, this freed the Skylanders from Kaos' ice spell, allowing them to defeat Kaos. The Book of Skylanders has since been relocated.
Despite not being a Skylander himself, Master Eon is also affected by the book, possibly for being its creator.
An altered version of The Book of Skylanders is shown in Season 1's opening credits, changed to show pictures of the main cast regardless if they are Skylanders or not, and with the show's logo added to the front.
It is possible the book was first seen in Skylanders: Trap Team, as the collection book from the Library. However, it was not named at the time.
The book is mentioned in most physical items obtained in the Skylanders Creator store, confirming it exists in the main canon.