The Vril

The Vril are a race of reptilian humanoids of unknown origin.

Biology
The Vril are bipedal, with two arms. They have shapeshifting and regenerative abilities. They are omnivorous in diet as they have been seen eating Humans, but they also do carry chocolate with Vril inside of it on their person when they travel to the surface. They have extremely long lifespans (most likely due to the Vril in their diets). Their appearance before adapting to Earth's atmosphere is quite gelatinous, possibly meaning that their reptilian look is not natural but is rather a result of the atmospheric conditions during the Cretaceous period.

Technology
The Vril managed to achieve spaceflight at least before the mid to late Cretaceous Period. They have a mastery over an energy source known as Vril, they have spacesuit and most likely have long known how to domestic animals.

History
The Vril arrived on Earth at an unknown point in the Cretaceous period. One member of the species gave some Vril energy to some early primates, a pair of monkeys named Adam and Eve, kickstarting the evolution of man. When an asteroid was about to fall to Earth, the Vril took their ship and several Dinosaurs down into the Earth's hollow core, where they founded the kingdom of Agartha.

After the devastation, the Vril played the long game, manipulating humanity until they could get them to wipe themselves out and they could take their place as the "rightful" rulers of Earth. After the atomic war which followed the invasion of the Moon Nazis and the subsequent fight for their resources that left the Earth in permanent atomic winter, the very Vril that created Humans went to humanity's new home in the former Nazi base, revealing to the daughter of the Human leader all the knowledge of the Vril race. With this knowledge, a group of Humans plunged into the Hollow Earth and they stole the Holy Grail. A Vril chases them to the Moon and is then killed by a falling air duct.