Ishtar (also called Inanna) was an important goddess of West Asia. Beginning at least by 3000 BC she was worshipped by the Sumerians, and by the Akkadians, and theBabylonians, and the Assyrians. Like most other female goddesses, Ishtar was a fertility goddess, but Ishtar was fiercer and more powerful than the Greek goddesses like Athena or Aphrodite. According to one story, when the Sumerian king Gilgamesh refused to be her boyfriend, she got angry and killed his best friend, Enkidu.
In another story, Ishtar is jealous of her son Tammuz, who brings life to the earth, so she kills him. Then everything on earth dies (like in winter). Ishtar is sorry, and she has to go beg her sister Allatu, the goddess of the underworld, to let Tammuz come back. But he can only come back for half the year, in the spring and summer – he still has to spend the fall and winter in the underworld. (Compare this to the Greek story of Persephone). People sacrificed animals to Ishtar, and prayed to her in her temples. The Akkadian priestess Enheduanna wrote poems to Ishtar (under her name Inanna).
After most people in West Asia converted to Zoroastrianism and Buddhism under the influence of the Persian Empire, around 500 BC, Ishtar gradually became less important to them.
Ishtar and Tammuz: A Babylonian Myth of the Seasons, by C. J. Moore (1996). Easy reading.
Gods, Goddesses, and Monsters: An Encyclopedia of World Mythology, by Sheila Keenan (2000). Easy reading.
Religion in Ancient Mesopotamia, by Jean Bottero (2001).