I realize this could get rock thrown at me, but I've only seen the original series of Star Trek, several episodes of Next Generation and some scattered ones from the other shows. I've also only seen the original Battlestar Galatica, the one with Lorne Greene and I don't think I've ever seen more than a few minutes of the reboot. (In my defense, I have seen all of the Stargates, but they're no longer on Hulu)
Anyway, my youngest started watching some kind of Power Rangers in Space kind of thing and in hopes of getting him to watch something else, I tried introducing him to Deep Space 9 because I knew it had creatures and thought it would be different enough for him.
He has now gone through the first eleven and though he's enjoyed them, he's said there haven't been any epic battles since the pilot, so he's wondering if I could recommend another show. I've suggested that he give the first Original a try, but in case that doesn't have enough action for an eight year old, I'm hoping someone could give me a hint about which Star Trek or whether Galatica might have enough to keep him on board.
Note: Firefly would also be an option, but there's only a handful of episodes and some of the storylines are kind of adult. Also it should be noted, we have HuluPlus.