Reply #20: "Day of the Dove", "The Doomsday Machine", or "The Immunity Syndrome"

[Deja Q]

Day of the Dove has an alien pitting the Federation and Klingons against each other for its own needs.

Doomsday Machine involves a planet destroying machine, presumed to have been created by an alien for war against an enemy of theirs, having wandered into Federation space and must be destroyed. (also a parable as to why armageddon-type weapons are not nice things to use.)

Immunity Syndrome sees the Enterprise battling a large organism capable of living in space. (on paper the idea must've sound stupid, but on screen it's very effective - and genius.)

Star Trek - the original series - is the ONLY series. TNG and the other spinoffs are their own little world. But I lack the time to go into a huge argument right now. :7