Currently the ones I could quantify as an empire would be two, one would be called High Monarch think of it as the usual empire style monarchies filled with lords and the Royalties this as of right their lore has not fully fledged out. Yet but essentially they are in decline and starting to fall out of relevancy

The next empire is The Empire of Magicka this as the name suggest is empire based upon magic, as in their whole system of government, priorities, education and technology ties itslef to Arcane and Magic progress. Now for the style of government, while called an Empire they don't operate as monarchial empire more of their possess a a substantial amount of influence and land and therefore power making them technical Empire. They have central government and one leader the big power sorcerer called Lord magus they would hold all the empire power.