He asked Captain Hamm, Big Mountain's security chief, to provide a shipment of cattle prods in order to control the night stalkers, who were becoming increasingly aggressive. Eventually, he evidently decided to face the night stalkers directly, an error in judgement that cost him his life. His skeleton, still clad in a lab uniform, can be found sprawled on the ground outside the night stalkers den. It is also possible that this event allowed the night stalkers to escape into the wild, leading to the further death of most of the scientists in Big MT with the escape of cazadores.
Dr. Calis was survived by evidently no one, and recalled with scorn by his colleagues, whose negative comments can be found on terminals scattered around the facility.
When asked why he created the night stalkers, Dr. Borous states that Calis dared him to splice together mountain lions, eagles, and condors, which somehow lead to a combination of coyotes and rattlesnakes.
- His skull is actually an apparel item, so if you use console commands to remove it his face is actually a disturbing-looking ghoul's face that is red, black, and a green mouth.
- Due to a requirement of the game engine, his limbs will still bleed like most normal corpses if severed by the player. If the body is moved around and if you look closely, you can see his head isn't actually connected to his body (there is no spine), but it still acts as though it's connected.
- Resurrecting and then talking to him will give the player the generic NPC "Hello and Goodbye" dialog choices and responses.
Dr. Calis is mentioned in numerous terminals in the X-13 research facility and also appears as a skeleton in the Fallout: New Vegas add-on Old World Blues. He can be found outside of the entrance to the former night stalker's reserve.