The beast

The beast was a giant monster that slept underneath the Isle of the Four Sisters. It was awoken by the Shadow Lord and destroyed the island in its rage.

Tales of Deltora
The beast inhabited a large island off the coast of Deltora, where it was kept asleep through the singing of four sisters. One day the sorcerer Malverlain came upon the island after being banished from his home, and upon hearing the singing of the sister, imprisoned them each on a corner of the island. When the sisters continued to sing despite the distance between them, Malverlain struck each of them down in a rage. When he killed the last sister, the beast awoke in a rage and began to rip apart the entire island until it sank into the sea.

It is unknown what happened to the beast after the Isle had been destroyed. The beast either dwells somewhere in the deep sea near the Isle of the Four sisters or drowned after the destruction of the Isle.

The four sisters from the Isle inspired the Shadow Lord to create his four creatures of the same name, and the the beast underneath inspired him to create the the grey tide, the latter of which was placed in the centre of Deltora. They were to be failsafes if all his other plans were thwarted.

The Sister of the South
Lief read about the beast when he read the tale of the four sisters after destroying the Sister of the South. He realised that the Shadow Lord had based the Four Sisters on the four sisters from the isle and later that he had based the grey tide on the beast from the tale.

Habitat
The beast lived underneath the Isle of the Four Sisters. It slept in the very rock the Isle rested on.

Anatomy
The painting in Tales of Deltora depicts the beast as a huge bipedal creature with extremely muscular arms and body. Its head is covered in horns and has multiple blue eyes. Its square jaw is filled with several long fangs. Its also has a long blue tail that curls like a whip.

Behaviour
The beast mainly slept underneath the Isle because the singing of the Four Sisters soothed it and kept it asleep. When the Sisters were struck down by the Shadow Lord, the beast awoke and it was furious. It immediately began destroying the complete island. The beast could have a very violent nature, destroying anything when awake or it was simply enraged because it had been woken from its sleep. It is clear however that the behaviour of the beast mainly consists of destruction and sleeping.

Diet
It is unknown what the beast ate but it is likely that it would devour anything.