Elements of the Cthulhu Mythos

The following tables and lists feature elements of the Cthulhu Mythos, that are often shared between works within that fictional setting.
The Cthulhu Mythos was originally created by writer H. P. Lovecraft in his horror short stories, although the term itself was coined later by August Derleth. Many writers, both during Lovecraft's lifetime and after, have added stories and elements to the Mythos. There is no central co-ordination of these stories, nor any oversight of the Cthulhu Mythos in general. Becoming part of the Mythos can be based on personal opinion and inclusion of certain elements of the Mythos is often debatable.
Overview.
Tables appearing under these entries are organized as follows:
Beings.
Great Old Ones.
The Great Old Ones are powerful, ancient creatures worshipped by deranged human cults. Many of them are made of an unearthly material with properties unlike normal matter. A Great Old One's influence is often limited to the planet where it dwells. If it is based on a planet outside the solar system, it can only extend its influence to Earth when the star of its planetary system is in the night sky. In such cases, the help of cultists performing various rituals may be required.
Outer Gods.
The Outer Gods have unlimited influence, unlike the Great Old Ones, and function on a cosmic scale. They include a subgroup known as the Lesser Outer Gods, or Other Gods.
Elder Gods.
The Elder Gods oppose both the Outer Gods and the Great Old Ones. Many consider them to be non-Lovecraftian, because they introduce a "good versus evil" dichotomy into the cosmic indifference of Lovecraft's fiction. However, others argue that these beings have no more concern for human notions of morality than the beings they oppose, and that humanity and the human world are beneath their regard.
Great Ones.
The Great Ones are the so-called "gods" of the Dreamlands, but they are not as powerful as the Great Old Ones and are not even as intelligent as most humans. However, they are protected by the Outer Gods, especially Nyarlathotep.