Board Thread:General Discussion/@comment-5461477-20160404225755/@comment-168424-20160405003222

Unfortunately, there are no easy ways.

The go to solution for the more technically minded is usually Pywikibot, a python-based bot. See Manual:Pywikibot/category.py for the category specific docs.

You could possibly do it with some extensions, but you would need to request their addition to your wiki from Wikia staff at Special:Contact/general. You have to be careful as misuse of these extensions can do significant damage.

Some extensions that can be used for renaming categories:
 * Extension:Replace Text
 * Extension:MassEditRegex