In the fictional universe of Star Trek, Exo III is a planet visited in the Star Trek: The Original Series episode, What are Little Girls Made Of?.
Exo III is a Class P world covered in ice. It is the third planet in the Exo star system. The planet once sustained an ancient civilization, whose ruins are now found underground.
Exobiologist, Dr. Roger Korby remained on Exo III for five years studying the ancient ruins. He discovered a machine that made realistic androids, and with the help of Ruk, one of the remaining original androids, Korby plotted to replace key personnel in Starfleet and the U.F.P. with android clones under his control.
Korby's plan was later foiled by the crew of the starship U.S.S. Enterrpise when they arrived on Exo III.
