You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: U.S. PRESIDENTS 
Clue: The last names of 8 different presidents end with this 3-letter combination
son

Category: BRITISH LEGENDARY POETRY 
Clue: The first edition of this collection of poems did not include "The Last Tournament"; it was added in the 1870s
idylls of the king

Category: CHARACTERS IN SHAKESPEARE 
Clue: This character is described as "a howling monster", "a most scurvy monster" & "some monster of the isle"

caliban