The Targetmasters were a line of
Transformers toys that consisted of two
robots; a
large one that transformed from robot to
vehicle or
creature; and a
small one that transformed from robot to the large robot's
gun. Actually the smaller robot was actually a human in a suit of robot
armor. (But technically, those were Nebulons in those suits; in the Transfomrers comic, Nebulons looked just like humans, but in the cartoon, they had green skin).
Also see
Headmasters.