Fictitious. (Merriam – Webster)
Having no real existence; fictitious: (Merriam – Webster)
Used to refer to something or someone who has been made very famous, especially by having many stories written about it, him or her. (Cambridge Dictionary)
Famous, especially by reputation. (Oxford Dictionaries)
Mythical; imaginary. (Oxford Dictionaries)
If you describe a person or thing as fabled, especially someone or something remarkable, you mean that they are well known because they are often talked about or a lot of stories are told about them.
The legend of fabled realms.
Fabled beast chronicles.
Fabled Legends: The Dark Piper.
Fabled ‘Gate to Hell’ really did kill people — and now we know why.