Anunnaki

The Anunnaki are mythological beings mentioned in Middle Eastern and Mesopotamian mythology, notably that of the Sumerians, Assyrians, and Babylonians. They are involved in the Babylonian creation myth. Altogether uninteresting for years until...

Appeal to cranks
The Bible code people feel that the Anunnaki are the Nephilim. But wait, the madness doesn't stop there! Apparently the Anunnaki tie into Zecharia Sitchin's cranky screeds, the Planet X/Nibiru silliness, and, of course, earth changes. The home planet of the Anunnaki is the tenth planet and is called Nibiry Anu. The Anunnaki built the Egyptian pyramids at Giza, nuked Mesopotamia, could bring the dead back to life, the weirdness just goes on.

The Anunnaki will return in 2022 or the world will end then, yet again or something.

Stolen fantasy
Few know that Sitchin wasn't the first to reintroduce the Anunnaki to 20th-century culture. In Robert E. Howard's short story "The Shadow Kingdom" from the August 1929 issue of Weird Tales, Kull of Atlantis (a precursor to Howard's better known hero Conan the Barbarian) battles and defeats the "lizard people" who enslaved humanity in a Pangaea like world. Kull would influence many of Howard's later works. Notably and on the subject, the main villain (Thulsa Doom) and the serpent cult in the 1982 Conan the Barbarian movie, were from the Kull series. Howard was an amateur mythologist and was well aware of Babylonian myths and deities which he used as inspiration in his fantasy and shared/exchanged information with H.P. Lovecraft to create a common mythos. Sitchin's Anunnaki seem to have more similarities with Robert E. Howard's lizard people than with the Sumerian Anunnaki deities mentioned in Gilgamesh.

Regardless the Anunnaki and their later correlation with Nibiru are an interesting case of 'modern syncretism' offering parallels to how Utanapistim became Noah and suggesting that myths are mastodon-tic cannibal beasts that eat everything in their path. Consequently, we can safely deduce that, eventually, we will have one, big, tidy, all-encompassing conspiracy theory that ties together Anunnaki, crop circles, ancient giants, the Illuminati and every other conspiracy theory. AMAZING!

First reference of Anunnaki (or the first and longest case of intellectual property infringement in history!)
The Anunnaki were 7 gods mentioned by Utanapistim (later Noah) to Gilgamesh as the old gods that sent the flood on earth. They are first mentioned in the Epic of Gilgamesh table 10. While these 7 deities later had Sumerian and Babylonian counterparts it is important to note that in the text these are presented as the gods of Utanapistim and not Gilgamesh. We can thus deduce that they were not Sumerian deities but rather were the gods of more ancient peoples (Utanapistim's). While Ea delivers the message to Utanapistim (and can thus be identified with later impersonifications in Christian and Hebrew mythology), An is the leader of this Pantheon and the people of Surrupak worshiped Enlil.

Ancient Greece
An, cruel father/ruler of these gods, was killed and substituted by his son Marduk and were later adopted by Hellenic cultures as Chronos and Zeus respectively.

Hebrew mythology
The problem presented by the plurality of Annunaki deities for a monotheistic religion was resolved with the invention of archangels under a single divinity (inspired by the Annunaki figure of Ea). This also presented the opportunity to transfer 'defects' or inconsistencies of the main divinity to its subjects.

Christian culture
The next step came as a result of the reduction of Archangels from 6-7 to 3, resulting in the main divinity (God) absorbing all the powers of the original 7 Anunaki. During the medieval ages and the redefinition of Satan, the undesirable traits of the 7 original deities were transferred to the devil.

Conclusion
The Anunnaki are much less boring than Noah's Ark, which has lost its appeal amongst conspiracy theories as it has no magic wielding, high tech, space-faring lizard people. Moreover, it is an opportunity to educate people against their will, by teaching them about syncretism and the hows of dynamic culture while they think you are telling them a story about aliens.