Toclafane
The Toclafane were the final evolution of the human race. They were cyborgs integrated into spherical, mechanical shells. The Master came up with the name from a fairy tale monster from Gallifrey, their equivalent of the boogeyman.
Biology
The Toclafane were the heads of humans from the year 100 trillion integrated into a dark-grey spherical metal shell. The spheres were a little over a foot tall and were sealed shut. They became a hive mind. Their personality was amoral and childlike.
Each Toclafane had built-in life support and teleportation systems. Concealed within the shell were extendable razor-sharp blades and spikes. The spheres were also equipped with red laser guns that could disintegrate life forms.
Appearances
The Sound of Drums (TV)
Last of the Time Lords (TV)
The Story of Martha (Prose)
The End of Time (TV)