A stackable, nestable pet shelter includes first, second and third housings. Each housing has a top of a predetermined shape and sidewalls that extend downwardly, and taper somewhat outwardly, toward an open bottom. In use, the bottom of the second housing rests upon the upper portion of the first housing, and the bottom of the third housing rests upon the upper portion of the second housing. The first and second housings are substantially hollow. When not in use, the third housing nests within the second housing which, in turn, nests within the first housing. An opening is provided in the sidewalls of the first housing for allowing an animal to enter or exit. The top of each housing includes an opening for allowing an animal to pass from one housing to the next.