What are some of the greatest (and strangest) nemeses your groups have gone up against?
For my group, it's each other.
There are two separate rogue traders in my group, and their retinues are split evenly between the other players. The two sides have entered into a rough alliance of convenience, with both hoping to eliminate the other before they get too powerful to take down in one fell swoop. Things, of course, are not going as planned, so they've instead settled on an arms race, with each side trying to be the last ship to land a crippling blow on an enemy vessel so they can claim it as a prize,and the first party down on a planet so they can claim it as a colony. It's pretty funny