The Beast is was a giant creature that the Shadow Lord awoke when we imprisoned the Four Sisters.
The Shadow Lord, before coming to Deltora, stumbled upon an island inhabited by four, singing, sisters. Raged by the Four Sisters singing, he imprisoned them. However, the sister's singing soothed The Beast and when it could no longer hear their voices, he awoke in a rage, almost destroying the island.
Not only is The Beast humungous, it has extremely muscular arms and body. It's head is covered in horns and has mutiple, blue eyes.<null> </null>