The difficult part about putting together a list of the best sci-fi television series of all time is that there are so many opinions on what sci-fi is. Then the generational thing comes into effect. Older viewers tend to like the classics more, while younger viewers look for special effects. Then the nerds find the mistakes made by the writers concerning the space-time continuum, etc.
Therefore, I just wrote my favorites down and ranked them, but I trended towards the classics. Here is my list of the top 21 TV sci-fi shows of the last century.
21 - The adventures of superman 1953-1957
This superhero show was the grandfather sci-fi. With the cast of Superman, Lois Lane, and Jimmy Olsen going against an array of criminals. It needed to be on the list as a break through sci-fi show.
20 - The New Original Wonder Women 1977-1979
The popular series brought the story of wonder women into the modern day with a 70's flare. Former beauty pageant winner, Linda Carter played the role of Wonder Woman after a television movie with Cathy Lee Crosby failed. For the role of Steve Trevor, the producers chose Lyle Waggoner, from the Carol Burnett Show. The show lacked many things, but it did have Carter in an amazing outfit.
19 - Babylon 5 1993-1999
Had stiff competition from the Star Trek shows, but build up a loyal fan base. In a UN-style setting, an Earth alliance is trying to prevent another war like the one recently fought. Had great characters and action, but I missed most of it as I was watching "ST the Next Generation".
18 - My Favorite Martian 1963-1966
A Martian crash-lands on Earth and is taken in by an amiable young man who agrees to protect his identity. Uncle Martin's (Ray Walston) special powers, invisibility, ESP, and telekinesis regularly get his host Bill Bixby into trouble with hilarious scenes.
17 - The X Files 1993-2002
The truth is out there... but trust no-one while trying to find it. Mulder and Scully investigate the FBI's X-Files, which seem to contain a pattern of alien activities. Government cover-ups and conspiracies keeping the truth hidden. Show took sci-fi TV to a completely new level.
16 - Battlestar Galactica 1978-1980
Bonanza's Lorne Greene in charge of a wagon train of spaceships fleeing the Cylon tyranny in search of the mythical world - Earth. Production costs saw the show canned after one season, but a letter-writing campaign saw it resurface for another Earth-bound round as Galactica 1980. Bad special effects, and worse acting, but people watched.
15 - 7 Days 1998-2001
The adventures of a chrononaut, Frank Parker,- a government agent who is frequently sent up to seven days back in time to fix things when they have gone wrong with the world. Parker travels courtesy of an invention that was created using alien technology from the Roswell crash; you have to love the site. They may not have left us any technology, but they did leave us some good TV.
14 - The Incredible Hulk 1977-1982
Based on the comic book, Bill Bixby plays the on the run scientist who has exposed himself to gamma radiation - occasionally turning into the Hulk (played by bodybuilder Lou Ferrigno) whenever he gets upset.
13 - Sliders 1995-2000
A Quantum Leap rip-off, but a good one. Playing with the concept of parallel universes, Jerry O'Connell and company keep jumping from universe to universe, while trying to find their way home.
12 - Roswell 1999-2002
For those of us that just love a good Roswell conspiracy theory. This was a fun show, which played off the fabled 1947 crash site in Roswell, New Mexico. There is lots of teen relationship drama and romance while the main characters try to get in touch with their alien selves.
11 - Lois & Clark (The New Superman) 1993-1997
The Superman saga with an emphasis on romance rather than sci-fi. My 5-year-old daughter loved it, and Teri Hatcher got here start here. Not a typical sci-fi, but a good story line, and fun characters kept the family watching.
10 - The Land of the Giants 1968-1970
Irwin Allen strikes again. A suborbital ship and crew passes through a portal to a land where everything is really big - although mysteriously Earth like in most ways. The show was fun, but the series was cancelled before the cast managed to make it back home.
9 - The Wild Wild West 1965-1969
Another old classic set in 19th-century America's Wild West. Good guy spies battle villains, including height-disadvantaged super scientist Dr Miguelito Loveless. A hit for CBS and after the premiere season the show was in full color. Re-runs remain extremely popular with sci-fi fans, but hard to find.
8 - Lost In Space 1965-1968
"Danger Will Robinson!" - An Irwin Allen great. Terrible effects, but a cult-favorite nevertheless. Swiss Family Robinson gets lost in outer space when the villainous Dr Smith stows away and knocks their flying saucer out of orbit. The robot usually manages to steal the show, and fans usually hoped Will would be zapped.
7 - The Outer Limits 1963-1966
This series is remembered for a few genuine great episodes. It seemed to try to ride the fame of T Zone, but a worthwhile series. Shatner, Nimoy, and Martin Landau all honed their credentials on the show.
6 - Kolchak the Night Stalker 1974-1975
A newspaper journalist with a nose for the extraordinary tracks all sorts of monsters, demons, aliens and other creatures. I loved this show when it first came out. Then saw it on late night reruns the other day, and felt a little ashamed I liked it.
5 - The Six Million Dollar Man 1973-1978
Badly injured astronaut Steve Austin gets some 'bionic' body parts and sets about carrying out impossible missions for a secret government agency. Lee Majors was just plain cool in the 70's. Favorite - The Secret of Big Foot
4 - Star Trek the Next Generation 1987 - 1994
Set 78 years after the original, the long-awaited new Trek series featured a good cast - the most popular being the android Data, Klingon bridge officer Worf, and Enterprise captain Jean-Luc Picard. Well written, and better acted then the original.
3 - Quantum Leap 1989-1994
Sam Beckett (Scott Bakula) wanders through time, but only in his lifetime. Facing an array of moral dilemmas while occupying other people's bodies. Somewhat confusingly, Beckett appears as himself to the camera, but the characters around him see only the body he occupies and cannot see his hologram sidekick Al. Favorite is series final, when Sam talks to God.
2 - The Twilight Zone 1959-1964
Perhaps the most famous sci-fi series ever, and done in black and white. Host Rod Sterling has set the tone with those amazingly delivered monologues book ending each episode. A cult classic and still a great one to watch on those Fourth of July marathons. Favorite- loved the one with William Shatner as a freaked out airline passenger.
1 - Star Trek 1967-1969
Seeking out new life and new civilizations - boldly going where no man has gone before. Captain Kirk, Spock, and crew warp around in the Enterprise. Sorry I am just a Trekky at heart, and at one time could name every episode. Favorite - Balance of Terror