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.
A title of nobility for a man ranking beneath a duke and above an earl.