Io was, in Greek mythology, one of the mortal lovers of Zeus. An Argive princess, she was an ancestor of many kings and heroes, such as Perseus, Cadmus, Heracles, Minos, Lynceus, Cepheus, and Danaus. The astronomer Simon Marius named a moon of Jupiter after Io in 1614.
Io wearing bovine horns watched over by Argos on Hera's orders, antique fresco from Pompeii
Juno Discovering Jupiter with Io by Pieter Lastman
Io Recognised by Her Father by Victor Honoré Janssens (second half of 17th century)
Hera and Io by Nicolaes Pietersz. Berchem the Younger (circa 1669)
Zeus is the sky and thunder god in ancient Greek religion and mythology, who rules as king of the gods on Mount Olympus. His name is cognate with the first syllable of his Roman equivalent Jupiter.
Zeus holding a thunderbolt. Zeus de Smyrne, discovered in Smyrna in 1680.
"Cave of Zeus", Mount Ida, Crete
1st century BC statue of Zeus
Zeus (centre-left) battles against Porphyrion (far-right), detail of the Gigantomachy frieze from the Pergamon Altar, Pergamon Museum, Berlin.