Zetan (Fallout)

Zetans are a species of Grey-like beings who have had many repeated run ins with the inhabitants of the irradiated wasteland which was once known as the United States of America, they have known of Earth and it's inhabitants since at least the 15th Century (possibly even longer) and have been abducting and experimenting on them ever since.

Biology
The Zetans are seemingly reptilian (or they just have a bad skin care routine ) they have three to four digits on each hand and have a binocular field of vision and they appear to be ether Oxygen or Nitrogen breathers as is displayed by their ability to breath Earth's atmosphere.

Their genetic code appears to be compatible with human genes (but it causes horrible Abominations)

They appear to have two variants. One variant we shall call the Invaders. The Invaders are your typical Little Green Men-types with