Budd Albright

After landing on planet M-113, the Enterprise is stalked by a creature which can assume the shape and form of anyone it chooses and which kills by removing the entire salt content of its victims' bodies.

When the Enterprise arrives at planet EXO-III to learn what has become of a certain Dr Roger Korby, he is found alive and well, but Captain Kirk has serious doubts about the good doctor's sanity when he learns of his plan to repopulate the Universe with androids - especially when he learns who is at the top of the list.