A ruler with absolute power; a tyrant.
A title awarded to senior members of the imperial family in the late Byzantine Empire, and claimed by various independent or semi-autonomous rulers in the Balkans (12th to 15th centuries)
The male monarch or ruler of an empire.
A large, relatively valuable marble in children's games.
Any of various butterflies of the subfamily Charaxinae.
Specifically, the ruler of the Holy Roman Empire; the world-monarch.
Any of various large dragonflies of the cosmopolitan genus Anax.
An emperor penguin.
The fourth trump or major arcana card of the tarot deck.
Any monarch ruling an empire, irrespective of gender, with "empress" contrasting to mean the consort of an emperor.
Any fish of the family Lethrinidae.