Cheyenne

 is Sunny's dog in 2280.

Background
Cheyenne is a native american tribe who lived in the "powder river region", here cleveraly adopted in use of the dog's name, and the powder keggers

Interactions with the player character
Sunny and Cheyenne help the Courier fight the Powder Gangers, if he helps Sunny kill a few geckos.

Appearances
appears in Fallout: New Vegas.