Bards make fantastic villains. They can be the puppetmaster whispering in the ears of leaders to cause wars, or they can be the flashy conqueror who gives a villainous musical number instead of a monologue.

Edit: Give the villain Vicious Mockery, and have them use it liberally. The players will want them dead.

Commoner: “Please! My children are so tired!”

Level 20 Bard: “cha cha, again!”