The golden goblin is a quest item used in the Grim Tales quest, acquired after killing a cloud giant named Glod found atop a giant beanstalk.
According to legend; a long time ago there was a greedy goblin named Gubblebak who was overseeing the smelting of molten gold when his goblin workers mutinied on him. Gubblebak tripped and fell into the vat of gold, and although he managed to escape he was still coated with the metal. He then jumped into a water trough, hardening the layer of gold and encasing him as the statue he is today.
Whether the goblin's origin story is true or not isn't known. Somehow the golden goblin was claimed by the cloud giant, Glod and must be killed in order to get the goblin and bring it to Sylas in Taverley to complete Grim Tales.
For an exhaustive list of all known sources for this item, see here
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