A Hobbit is half the size of a Human, a Dwarf a bit bigger than a Hobbit. A Balrog, about 13ft tall, a unicorn ?, horse sized, Mermaid/Merman/undine as big as a human. Orcs/goblins, Uruk hai, around about human size. Centaur, Horse sized, Werewolves, Vampires, Zombies/revenants..human sized though in the case of the werewolf..in one form, a bloody big dog. Golem...depends on how much mud is available. The above need to be 1/72nd scale (for my collection
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Though the above is a tiny Proportion of mythical/Fantasy critters and with a lot of em, giants for example size is anyones guess.