6. “Regeneration” – Star Trek: Enterprise
If you want spookems and freights, the best bet is to call up the Borg. The boogeymen of the Star Trek universe appear in all three of the post-original series, The Next Generation, Voyager, and Enterprise. While Enterprise pre-dated The Original Series and the Borg were only introduced in The Next Generation, the workaround that the episode came up with is quite brilliant.
The story is actually a sequel to the Star Trek: Next Generation film, First Contact, where the Borg go back in time to try and stop First Contact from happening. That event, when Humanity launches its first warp speed engine, and in doing so indirectly invites the Vulcans to Earth for the first time is a landmark moment in the history of Earth.
The Borg sought to prevent that from happening but were stopped by Jean-Luc Picard and the Enterprise. While it’s not known how The Borg ended up frozen in the Earth’s Artic, a group of humans awakens the mechanical space zombies, and the Enterprise is left to try and stop them with their inferior tech.
It may be the scariest episode involving the Borg yet, simply because it asks the question of “how do you stop a threat that’s a couple hundred years away from needing to be ready for?”
It’s also one of Enterprise’s best episodes.