Verified answer

Let's see, in no particular order:

Minotaurs

Unicorns

Elves

Fairies/Faeries

Miniature... things (like Smurfs)

Dragons

Wizards

Vampires

Werewolves

But if you put a really good spin on a common myth, it makes it better. Like, if you have vampires, instead of making them burn in sunlight, you can make them sparkle!!! ...oh wait.

Kidding :) if you have a good story with good characters, it's worth writing.

♥

It depends on what you define as "mythical" if you are worried that your story is not worth writing then maybe it is time to slightly tweek it instead of giving up on it. No matter how much you are convinced that you have come up with a completely new original unique fantastic plot I can guarentee you every idea has been taken. So instead of avoiding cliches use them but tweek them slightly to make it work. Instead of the dumb blonde bimbo as she is perceived make her out to be an excellent fighter. So if you are afraid your story will be seen as cliche tweek it so it will seem more real and interesting.

Dragons are the most overused.

Wizards.

Vampires.

Zombies definitely.