The Deepcoiler
Species: Reptile Place of Origin: Great Inland Lake Gender: Unknown Weapon: Natural Defenses Death: Killed by Samkim
Books Appears: Salamandastron Mentioned: Marlfox

The Deepcoiler was a horrible monster, described as a huge underwater serpent, that lived in the Great Inland Lake. Shrews thought it to be only a legend, but found it to be a frightening reality. It was said to be more than three boat lengths in size. The creature attacked many times at random during the recovery of the Blackstone, it caused the deaths of many creatures including Spriggat and Dethbrush; the Deepcoiler also killed a number of shrews and nearly killed Tubgutt.

The Deepcoiler was killed by Samkim after he thrust the Sword of Martin into the roof of its' mouth. When the Deepcoiler tried to close its mouth, it pushed the sword up into its brain, thereby killing itself. Its body later washed up on shore, where it was found by Mara, who retrieved the sword. Mara later met up with Samkim and returned it.

The Deepcoiler is later referred to as a "lake monster" by Ellayo Swifteye when she told Friar Butty an old story about Marlfox Island that she heard from her father.