Starblazers
A plucky crew of humans takes to space in the sunken battleship Yamato, repurposed as a spacecraft, in this melodramatic, thrilling animated space opera. The crew of the Yamato are never anything less than awesome, and the show really gives a feeling of space travel being slow and dangerous — but the show's real standouts are the villains, especially the sly Desslok and the chilling Comet Empire.
3rd Rock From The Sun
Where so many series depict humans exploring alien cultures, 3rd Rock suggested that aliens would be equally fascinated by exploring Earth. After an awkward crew of alien explorers decides to extend their stay on Earth, they try to integrate into human life in suburban Ohio, though they're often baffled or overwhelmed by human culture. It's worth watching for its dead-on satire of academic life, as an alien has surprisingly little trouble fitting in as a college professor.
Greatest American Hero
A high-school teacher gets hold of an alien suit that lets him become an amazing superhero — but he loses the instruction manual. It's a silly premise, and the show uses it for maximum slapstick effect, but it's also one of the first shows to do superheroes justice on television.
Adventures Of Brisco County Jr.
A postmodern weirdo scifi western with Bruce Campbell in full 1990s hotness mode, Adventures of Brisco County Jr. is a cult favorite for good reason. Hilariously written and packed with funny references, the show is about Brisco's quest to avenge his father's death – and to discover futuristic things like blimps and Led Zeppelin. Must be seen to be believed, especially if you are a Middleman fan.
Ultraviolet
Before there was True Blood, there was this grown-up, sophisticated look at vampires — a secret paramilitary force uses high-tech methods to track down vampires hiding in Britain. Tense, taut and relentlessly weird, this show brings an X-Files vibe to the vampire's lair.
Sliders
Physics student Quinn Mallory develops a device that allows him to "slide" between alternate universes, and he and his friends quickly find themselves unable to get back to their own version of Earth. Each episode is an exercise in alternate history, with the team sliding to a new universe in the hope that they'll eventually find their way home.
Red Dwarf
Originally more a sit-com that happened to take place in space than a real SF show, the longer this British series continued, the more it started investigating the possibilities of the genre in ways that "real" sci-fi hadn't thought of. Worth it for "Better Than Life" and "Back To Reality," if nothing else.
Space: Above And Beyond
To quote from Jesse Alexander's io9 guest blog, "Before Apollo and Starbuck began frakking and fighting in Battlestar Galactica, the Wildcards of Space: Above and Beyond were dogfighting in their Hammerheads, bar-brawling with in-vitro hating racists, and elbow-deep in martian mud as alien artillery screamed from the sky... [The show featured] twenty-four compelling episodes about relatable, almost ordinary characters overcoming extraordinary challenges through teamwork and sacrifice... S:AB was also one of the first shows to treat high quality visual effects as just another narrative tool."
Knight Rider
In most shows, it would be a bad thing if the hero's car had more personality than all the other characters put together. But in this show about an artificially intelligent set of wheels, it's the jumping-off point for a great buddy cop show. Just pretend they never tried to remake or continue this classic.
True Blood
The vampire series True Blood strives to fill every sick fetish you didn't even know you had. In an alternate reality, vampires have come out of the coffin — no longer do they hide from society. And vampire-human assimilation is a very tricky thing, especially when all the characters hate each other, sleep with each other, and have to fight off giant sex-partying demons together. But the show's at its best when it goes whole-hog bananas.