They're not zombies, they're a mutant strain of humans evolved over centuries of lightless/cannibalistic/biological contaminated existence in the bowls of a spaceship.
Sci-fi Horror Rocks! But not all Sci-fi Horror Movies stand up.
IMO:
Event Horizon was good up until Hell showed up and over-abundance of splattergore ruined everything. If the ship had actually been possessed, rather than Sam Neil chewing on scenery, would have been much better. Great sets/FX. C+
Supernova was good for all of 5-10 minutes before the plot kicked in. Spader was ripped in this one. He really rolled down hill on Boston Legal. OK sets/FX. Ass
Sunshine was pretty great throughout. I like this one and don't mind the craziness at the end. Excellent sets/FX. A
Pandorum is also pretty great. I quite enjoyed all aspects of it. The action, acting, setting, mood, were all well done. Excellent sets/FX. A
Sphere - I'll include this, since it was mentioned, but there's not much of a horror angle to this one, more of a WTF is going on/time travel/superpowers angle. The set-up was great, finding/exploring the spaceship was great, everything else was awful. Shockingly, Hollywood managed to ruin an excellent Crichton novel. Decent sets/FX. D