Earth was an imperfect sphere. (TV: The Blood Line)
Nestene energy units were hollow spheres. (TV: Spearhead from Space)
Torchwood London referred to the Void Ship as "the Sphere". (TV: Army of Ghosts)
The Toclafane appeared as human heads encased in metal spheres. (TV: The Sound of Drums/Last of the Time Lords)
Mechanoid Interceptors were giant, spherical warships used by the Mechanoids in their encounters with the Daleks. (COMIC: Eve of War)
Behind the scenes
A sphere is the set of all points equidistant from one particular point in three dimensional space.