Zombies shouldnt have any special abilities.. they are dead, be happy they even walk.
The only ability maybe would be they invade in big groups.
Are perfect, although i picture them with an "advance technology space armada"
I wouldnt like for them to be underestimated.
Jump Ship Troopers, this ants float from their spaceships and land on yours to puncture holes outside the hull. They also swarm in teleporting mode with regular ant troopers.
They should have a special team dedicated to sabotage your ship weapons and shields.
I also think we should have the following space creatures (to fight with)
Mythical Space Squid, that attacks ships, chances of confronting him are low.
Some legends say the creature destroyed a full Antorian Fleet. (The animations would be ; the squid slapping your ship (making everyone inside tremble and fall down).
A gigantic worm that lives in space and feeds off radiation. Chances of encountering him woild be medium. (The animation would be the worm stretching to take chungs of your hull walls).
This are encountered in far away galaxies from Sol.
Some sort of fish like form with many sharp teeth that travels in space along its pack of fellow species. (The animation of attack would be they eating your hull walls, and moving in your halls to eat your crew)
A slimy liquid like creature that spits acid at your armada. The acid is powerful enough to meld your hull walls.
A bug that travels in the sol system floating flapping its wings. It shoots a larva that penetrates your hull then releasing a earth worm like bug that swallows your crew alive.
Dormidian Araneae :
Hard to spot them, but are very powerful space spider that jumps in your hull and finds a way in your space ship. If you kill it; it will release fast moving spiders that its bits will knock your crew to sleep, the eat them.
If only we could hear you scream in space.