Melkor's depiction by artists: Flawed?

[Kuruharan]

...but I've never allowed silly things like that to stop me.

It's safe to assume that Melkor would've been the tallest, being the Dark Lord and all that. Knowing Melkor's personality we can conclude that he would not allow one of his servants to be taller than himself.

There is a possible exception to this though. His dragons would have been "larger" than he was. I guess it would be up to the reader's imagination whether a dragon standing on its legs would have been taller. If it was a winged dragon the wings would probably add to the height (even when they are folded).

Now this may just be an exception that proves a rule...

Also, I'm probably not well equipped to discuss dragon sizes and heights because my mental picture of them has evolved considerably. I had originally pictured them as being huge beasts that would tower well above humans and elves when standing on their legs. However, my picture has changed considerably. Due partially to the realization that this type of dragon would be ill-suited to the underground life that dragons preferred and partially to seeing Tolkien's own picture of Smaug they have become decidedly more snake-like and lower to the ground.

(It is kind of hard to disagree with how Tolkien drew Smaug in my own view).

However, I guess it could also depend on where the legs are and the structure of the neck whether a dragon would have been taller than Morgoth.