Star Trek: 10 Worst Alternate Realities We've Seen (So Far)

Starfleet's early days weren't a purely peaceful jaunt out into the unknown. While the excitement of space travel was etched into the bulkheads of Enterprise, there were dangers waiting for the NX-01 that none from their time could see.

The Sphere Builders needed to take some pieces off the temporal playing field, so they manipulated the Xindi into staging a preemptive attack on Earth. With seven million lives lost, Starfleet cancelled all exploration missions and focussed its resources on tracking the Xindi down.

The stakes were devastatingly high. While that first attack was but a taste of what could come, one potential reality saw Earth destroyed, with the survivors limping toward, though they didn't know it, a planet that would soon explode into so much space dust. 

Dr. Phlox managed to change the past, avoiding this dark twist of fate, but once again the audience were treated to innocent bodies blasting out into space.