Being

The Beings are an immensely powerful, omnipotent species who once visited Earth and were worshipped as the Greek and Roman gods including Zeus and Apollo. When humans' faith in the Beings began to disappear, the Beings withdrew to Pollux II, where they would wait to be worshipped again. After many centuries, only Apollo remained in the physical realm, waiting alone for humans to find him. (NF novels: Gods Above and Stone and Anvil).

The 23rd century
In 2267, the USS Enterprise (NCC-1701) was drawn to Pollux IV by Apollo. Apollo wanted to make the crew of the Enterprise worship him, but his plan was ultimately defeated by Captain James T. Kirk, and he joined his fellow Beings. Before he joined the others he impregnated Enterprise archaeology/anthropology officer, Lieutenant Carolyn Palamas. 

Following the visit of the Enterprise to Pollux II, it was theorized that the Beings had also visited other worlds in addition to Earth, such as Vulcan and perhaps Romulus as well. (Startrek.com article Strange Relations: Romulans and Vulcans).

On stardate 2901.1, the Enterprise encountered more Beings on an unidentified planetoid in the Perseus Arm. This time, however, they encountered not only Apollo but the entire pantheon of Greek Gods! When Kirk, Spock and McCoy beamed down to investigate the planet, they found themselves reliving Homer's Odyssey, right down to the gigantic cyclops they encountered, and soon discovered that Zeus was orchestrating this.

Using the ship's power, they blasted Zeus with a tractor beam from orbit, making him lose his footing. Ashamed, Zeus and the other Olympians left, taking Mount Olympus with them. The local inhabitants of the planet were then left to fend for themselves. 

Mark McHenry
Mark McHenry was a Starfleet Academy student who had an extraordinary ability to perceive the universe in ways that no other human could. He was able to find his location in space without the use of star charts or technology. He wanted to be a navigator aboard a Starfleet ship and trained to do so. (TNG novel Worf's First Adventure)

Unbeknownst to his friends, he was actually the descendant of Lieutenant Palamas and Apollo; some of Apollo's godlike power had surfaced in him. Furthermore, he'd had a childhood "Imaginary friend" who turned out to be, making herself invisible to everyone but him. 

Excalibur
In the late 24th Century, the USS Excalibur (NCC-26517-A) encountered the full complement of Beings, living in a region of Sector 221-G. At first they negotiated with the Beings, who offered Ambrosia, the "food of the Gods", to all who would follow them. When Captain Calhoun refused, the Beings attacked, and in the ensuing conflict, the beings seemed to have been destroyed, with the exceptions of Woden, Mark McHenry, and Moke. 

Known Beings

 * Zeus
 * Apollo
 * Circe
 * Anubis
 * Mark McHenry
 * Moke
 * Thoth
 * Aphrodite
 * Loreck Avery
 * Quirinus
 * Carmentis
 * Ceres
 * Falacer
 * Furrina
 * Palatua
 * Pomona
 * Portunus
 * Volturnus
 * Janus
 * Orcus
 * Liber
 * Ceres
 * Juno
 * Pales
 * Salus
 * Fortuna
 * Fons
 * Fides
 * Vediovis
 * Summanus
 * Larunda
 * Terminus
 * Quirinus
 * Vortumnus
 * Lares
 * Pales
 * Salus
 * Fortuna
 * Fons
 * Fides
 * Vediovis
 * Summanus
 * Larunda
 * Terminus
 * Quirinus
 * Vortumnus
 * Lares
 * Vediovis
 * Summanus
 * Larunda
 * Terminus
 * Quirinus
 * Vortumnus
 * Lares

Possible Beings

 * Quetzalcoatl