Some sci-fi TV shows have gotten even better with time and make for a great re-watch. One of the most entertaining things about watching an older sci-fi show or movie is to see how they envisage the future. Back to the Future has proved that self-tying shoes and flying cars may not be one of humanity's top priorities, but watching a show about the future, made in the past, can be both frightening and hilarious.

Viewers have also always been curious about discovering other planets or alternate realities. Some series tend to tackle the subject with care and trepidation, while others focus on a more lighthearted approach. But, the true beauty of the classics like Star Trek don't even need to be mentioned, some relatively old shows from the last 20 years or so shouldn't be forgotten either.

10 Warehouse 13 (2009-2014)

It's About What's In The boxes

One of the jewels in the crown of the Syfy channel, this action comedy had one of the highest-rated debuts in the network's history. The mix of historical facts with elements of the supernatural made this show not only entertaining but also educational. There was undeniable chemistry between the two leads, Eddie McClintock and Joanne Kelly, as the will-they won't-they trope was enjoyable to watch.

Each episode presented a raucous ride across history, with a host of well-known faces from the world of sci-fi TV.

The premise of having a huge storage unit filled with otherworldly artifacts is one with unlimited potential. This was evident in the fact that it lasted an impressive five seasons, and included things such as Marilyn Monroe's magical hairbrush, and Agatha Christie's typewriter, to name but two. Each episode presented a raucous ride across history, with a host of well-known faces from the world of sci-fi TV. Kelly Hu, Joe Morton, and Kate Mulgrew all appear in this fun show.

9 Sliders (1995-2000)

Quantum leaping gone wrong

A miscalculation during a wormhole jump leads a group of friends (and some stragglers) to travel between alternate Earths. Using a handheld device with its very own set of rules, they find themselves in worlds where men are ruled by women, and the English have won the Revolutionary War.

They encounter interdimensional doppelgängers, alien species, and alternate versions of historical figures, all while trying to make their way back home. The series went through a few different networks and cast iterations, which can be felt between certain seasons.

However, there are plenty of stand-out episodes which remain as fun today as they were in the late '90s. Jerry O'Connell headed up the cast for most of the show's run, bringing his goofy yet charming brand of leading man energy. With plenty of laughs to be had, and wild worlds to be explored, Sliders introduced an innovative concept that stood the test of time.

8 Fringe (2008-2013)

What Lies Beneath

J.J. Abrams was one of the creators of this atmospheric show that balanced the line between reality and a parallel universe. Part of a prime-time sci-fi resurgence of the era, Fringe combined elements of a mystery-of-the-week format with an overarching thread that held everything together. Joshua Jackson and Anna Torv lead the cast with otherworldly charisma and chemistry.

Both the "Over Here" and the "Other Side" are places filled with exciting storylines, and whenever they overlap, drama is sure to follow. The show developed a cult following over its five years, delighting viewers with standalone episodes, as well as mysteries that spanned seasons. Fringe may feel somewhat retrained in its lack of excessive showiness, but under the surface lies a world of fascinating tales to be discovered.

7 3rd Rock From The Sun (1996-2001)

How Aliens See The Earthlings

There aren't that many sitcoms that embrace the sci-fi genre, but this one managed to make it work in a non-gimmicky and highly entertaining way. The stellar cast includes John Lithgow, Joseph Gordon Levitt, and Jane Curtin, who were given some hilarious material to work with.

A simple concept of an alien expedition wanting to study Earth roots the show in a kind of palatable reality that works within the lighthearted comedy genre. Its eight Emmy Awards speak volumes about the quality of the show.

The audience quickly forms a bond with these "aliens from outer space", and gets to enjoy how they adapt to their new Earthly ways. There's a boundless comedy, quirky romance, and a cameo from William Shatner, which is a wonderful pay-off to a long-running gag. With episodes all timed under half an hour, it's a binge-worthy classic that puts a humorous twist on an often serious genre.

6 Stargate SG-1 (1997-2007)

The Door To The Future

First, was the original Stargate film from 1994 - a smash hit that was a breakthrough for Roland Emmerich. Then, came this spin-off, which launched a franchise spanning decades. Expanding the worlds built in the original, this 10-season action adventure travels space and time, exploring new planets and civilizations. While the stars of the movie weren't able to reprise their roles, actors such as Richard Dean Anderson and Michael Shanks made their mark.

The stakes get higher as the seasons progress, with countless lives to be saved, and many threats to the gate to be fought.

The big-budget special effects were very innovative at the time, creating visuals that still look good to this day. The cast of characters features astrophysicists, Egyptologists, military personnel, and a plethora of multi-dimensional beings, providing interlocking storylines that thrill and entertain. The stakes get higher as the seasons progress, with countless lives to be saved, and many threats to the gate to be fought.

5 Quantum Leap (1989-1993)

The Original Slider

Scott Bakula's iconic role served as a template used by similar sci-fi series for years to come. A brilliant doctor gets stranded in time, trying to make his way back to his reality. Perhaps, slightly ahead of its time, the show took a while to find its core audience, but once it did, it built a devoted following. Thirteen million viewers tuned in to watch the finale, and even more have been discovering the show over the years.

As Dr. Sam Beckett "leaps" into the lives of various people through many realities, he tries to change their past so he can fix the future. Each adventure utilizes the fact that he's a highly decorated scholar, martial arts expert, and talented artist, taking audiences on a thrilling ride. Well worth a watch, as the futuristic nostalgia is real.

4 Battlestar Galactica (2004-2009)

A Journey Through Space And Time

Technically, the pilot for Battlestar Galactica is a two-part miniseries that aired in 2003. The plot does not hesitate to ease the audience in, as a whole colony of planets is wiped out, leaving only a handful of survivors. With that, those aboard the remaining fleet of ships must try and make their way to "Earth".

Everything that happens afterward is a masterclass in sci-fi adventure. The ongoing war with the Cylons takes many turns, with allegiances changed, and loyalties broken. The cast has a magnetic on-screen presence, and the interpersonal relationships are as interesting as the interstellar ones. Part space opera, part political drama, and add to this, one of the most satisfying and mind-bending finales, Battlestar Galactica is the gift that keeps on giving.

3 Star Trek: The Next Generation (1987-1994)

A Franchise That Lived On And Prospered

The first to revive the beloved franchise, this sci-fi juggernaut introduced audiences to Captain Jean-Luc Picard (Patrick Stewart) and his crew aboard the Enterprise NCC 1701-D. Set in the 24th century, the adventures take the starship to many planets within the Star Trek universe, mixing themes of discovery, war, and diplomacy. The time between the end of the original, and the beginning of this version, meant that many viewers were only then being introduced to this iconic franchise.

The successful revival attracted many stars, including Whoopi Goldberg, and even saw the return of Leonard Nimoy. Audiences became enamored with the new Enterprise crew and enjoyed exploring the new worlds and issues they faced. Multiple spin-offs and reboots followed, and it's safe to say that without The Next Generation, it might not have happened.

2 Smallville (2001-2011)

Before There Was Superman

There had been many successful iterations of Superman's story, but this was the first to focus so closely on his teen years. Viewers were able to be by his side as his abilities slowly developed, and he eventually learned about his otherworldly heritage. The word "Kryptonite" wasn't even uttered until the story was a few seasons in, and the relationship with Lois Lane was a very slow burn. Viewers were kept waiting a long while before he even donned the blue and red suit.

This helped build one of the most well-rounded versions of Clark Kent in the character's on-screen history.

It started as a mystery-of-the-week format that focused on individuals affected by the "meteor strike" in a rural Kansas town. The series took its time before diving into the mythology the audience was familiar with. This helped build one of the most well-rounded versions of Clark Kent (Tom Welling) in the character's on-screen history. His romance with Lana Lang (Kristin Kreuk) was explored to its fullest, as was the layered relationship with Lex Luthor (Michael Rosenbaum). With a host of new and familiar ing characters, and a lot of action, Smallville is still as entertaining as it ever was.

1 The X-Files (1993-2018)

To Believe Or Not To Believe

One of the biggest, most successful television shows of the 1990s, this sci-fi staple introduced the world at large to the paranormal and the unexplained. Special agents Fox Mulder (David Duchovny), and Dana Scully (Gillian Anderson) became household names, as every week they faced a new monster or another supernatural event. The juxtaposition between his love of conspiracy theories, and her level-headed approach led, to many explosive moments between the beloved duo.

As the years ed, and they dove deeper into the unknown, viewers were hooked on the mystery as well as the chemistry. The show was a ratings success and won multiple awards, with its initial run lasting until 2002. Then came a revival, with additional seasons premiering in 2016 and 2018. The legacy of this sci-fi stalwart is undeniable, and it's as unnerving and engaging now as it was back in 1993.