Can we please have the-lord-of-the-rings and lord-of-the-rings as synonyms? In SFF, the latter is popular and in Movies.SE, the former. I think both are likely to be used here. (I personally prefer the former as the master, but either would do.)
But a tag synonym isn't necessary here. This is a short-term problem because the reputation to create new tags is lowered to private-beta/boot-strapping levels. Once the site gets going, it becomes much harder to inadvertently create new tags where a simple variation already exists. Text completion helps guide users to the correct usage:
lord → the-lord-of-the-rings
Synonyms were intended to link two completely separate words meaning essentially the same thing (think 'car' vs 'auto'). Everything else only bulks up the tag listings needlesslly.
Yes we should and now we have question with both the tags too.
But it's better to keep the-lord-of-the-rings as the primary tag as it's part of official name too.