I was just looking at the TV Tropes page for "The Dragon" the other day and this same question occurred to me. In that case, the answer is fairly simple: One page will be entitled Dragon, for the mythical beast; the other will be The Dragon, for the Bad Guy's Evil Lieutenant. This follows the usage of both Wikipedia and TV Tropes, and since we've been stealing so much from them so far, we might as well steal that too. Then in the text of the article we can say, (for example):
"For the mythical beast covered in scales, see Dragon;
or:
"Sometimes a dragon is also The Dragon but not always."
One thing I've been trying to do (with varying consistency), is use Wikipedia and TV Tropes as a style guide. For example, I was sorely tempted to name the People page I just posted last night "Wrong Way Corrigan", because that's the name I'm most familiar with and because it's a more striking, more memorable handle. But he is listed in the Wikipedia as "Douglas Corrigan", and so for consistency's sake, I followed Wikipedia's example
