Little gecko (Fallout 2)

The little/normal geckoes are the easiest of them to kill. They appear quite early in the game. (already in the Fallout 2 Quest - Rescue Smoke, where they roam the Arroyo Hunting Grounds) They can be skinned, if you have the Gecko Skinning perk.

Little Geckos have horrible detection AI, and it is often possible for the player to walk right in front of them and not be noticed. This makes it easy to get inside attack range without being caught.