The Sea of Stars is full of villains, how could it not be?, ranging from (arguably) the Empress down to petty bandits and thieves. But for this we will confine ourselves to the upper levels of villainy.
How does one define villainy in a world ruled by dragons? Some would place the Empress as the most vile of villains, after all, it was her machinations that caused the downfall of the gods and lead to the Sundering. Yet, for all that, she is not much of a villain now, her domains are ruled with a light touch and she keeps order using the minimum of force needed. it could be argued that she is now a force for, not good, but stability and peace. Certainly, her death would be likely to through the whole world into chaos.
Now, Ba’ai’ai, the Dark Star, is a villain without doubt, a ancient and mighty dragon seeking only to expand his personal power whatever the cost to others. He even built an Empire slaved to his dreams of power and conquest. His ambition will lead directly to the most bloody and destructive conflict the Sea of Stars has seen, the Nightmare War.
The government of the High Kingdom of Laccini, using necourgists, money and military force to expand their influence. A much more human threat but still dangerous and persistent.
The Sen’tek still plot and scheme to overthrow the Dragons, seemingly careless of who and what else suffers, their initial attempt to tear them down having failed. They will provide aid and weapons to anyone who will strike against the dragons and the Imperium for whatever reason, the Sen’tek just want the dragons destroyed because only then will they be safe.
Notes: Late again, sorry. Been busy. There are more villains of course, but this is a start.
Image “The Dragon Devouring the Companions of Cadmus” by Hendrick Goltzius (Netherlandish, Mühlbracht 1558–1617 Haarlem), after Cornelis Cornelisz van Haarlem (Netherlandish, Haarlem 1562–1638 Haarlem) via The Metropolitan Museum of Art is licensed under CC0 1.0