Although still deemed scientifically impossible, time travel remains one of the most often used tropes in science fiction, especially on television.

Time travel is so appealing because it gives everyone a do-over and offers a chance to fix some of the biggest mistakes made in history. It's become a fascinating topic of conversation as we ponder questions like "What if I traveled back in time and killed Hitler?" "What if I traveled back in time and didn't date that guy who I later learned was a jerk?" "What if I could do something to prevent a loved one from dying?"

That's probably why time travel remains an important element in science fiction. And for those looking to get their time travel fix, there are plenty of television series on streaming subscription services to fulfill that need.

Here's your guide to finding time traveling shows on Hulu, Netflix and Amazon Prime.

Doctor Who

Streaming On: Amazon Prime

The mad man in the blue box is infamous for his traveling through space and time, and thanks to a deal with the BBC, he is currently living his adventures, at least in his modern incarnations (nine through 12), on Amazon Prime.

For those not in the know, The Doctor is a time lord who stole a time machine, a TARDIS, and ran away from his planet of Gallifrey. He often picks up companions to travel with him, and they make their way through time, saving the world more often than not, while discovering that life with The Doctor isn't always as easy as one might think.

For those looking to stream the classic Doctor Who episodes, though, you're still out of luck. None of the classic Who episodes appear anywhere online for streaming. That's a pity, too, because the DVDs are occasionally hard to find and even when they're available, collecting 50-plus years of a television show can get expensive. But for those wanting to catch up on the new series, Amazon Prime is the only game in town.

The Time Tunnel

Streaming On: Hulu

The Time Tunnel takes us back to 1966 science fiction television. Inspired by a 1964 movie The Time Travelers, the series starred James Darren and Robert Colbert and had exactly one season with 30 episodes.

The show is about a top secret U.S. government project to build a time machine called "The Time Tunnel." The decades-old project gets investigated by a U.S. senator who must determine if it's worth its cost. That Senator insists that he won't continue funding the project unless he can see someone travel through time and then return. That trip through time happens, but the two who volunteered for the trip become lost. The series follows the adventures of those two characters as they bounce around from one time period to another. This allows the two men to witness some of the most incredible moments in history: the sinking of the Titanic, the attack on Pearl Harbor, Custer's last stand and even the Battle of the Alamo.

11.22.63

Streaming On: Hulu

11.22.63 is Hulu's exclusive adaptation of the Stephen King novel of the same name. The series is about teacher Jake Epping as he discovers that a local diner has a closet that can send anyone back to 1958. The owner of the diner, Al, wants Jake to continue a time-traveling mission that he started: to prevent the assassination of JFK.

Jake soon finds out, though, that changing the past isn't easy. The past has a bad habit of pushing back, often putting those he cares about in harm's way. Jake also becomes sidetracked after falling in love with a fellow Texas teacher, Sadie, and eventually, he has to decide what's most important to him: Sadie or potentially saving the world.

Jake must balance the things that make him happy while desperately following a string of clues to discover if Lee Harvey Oswald acted alone upon that fateful day.

DC's Legends of Tomorrow

Streaming On: Hulu

DC's Legends of Tomorrow is a spin-off series from Arrow and The Flash that combines superheroes with time travel. Former Time Master Rip Hunter recruits a team of misfit superheroes to help him stop the villainous Vandal Savage from destroying the world. But what's most important to Rip is that he wants to prevent Vandal from killing his wife and daughter.

The team of superheroes find themselves flung from one time period to another, in a race against time as Vandal puts pieces in place for his ultimate takeover of the world. Things don't always go according to plan, and some team members die, meaning that the stakes become higher with each trip through the past, present or future.

In the meantime, the Time Masters have sent others after the Legends, upset that Rip has decided to go against one of their main directives: don't interfere. So Rip and the team must dodge their pursuers in their effort to stop Vandal once and for all.

Primeval

Streaming On: Hulu, Amazon

Primeval is a British science fiction series that originally aired in the United States on BBC America. It had a total of five seasons, meaning there's plenty of time traveling goodness to enjoy. The series revolves around Professor Nick Cutter and his group of associates and friends who spend their time investigating strange anomalies that occur around the world that allow one to travel through time. Often, that means that dangerous creatures, such as dinosaurs, often manage to get through to the modern world.

Not only does the team have to track these anomalies and protect the world from what goes through them, but they also must protect their own timelines, which often get altered after they travel through the small wormholes themselves.

Primeval is a nice cross between Jurassic Park and Doctor Who, with a little bit of Land of the Lost thrown in for good measure.

Quantum Leap

Streaming On: Hulu, Netflix

One of the most popular time travel shows of the decade followed Dr. Sam Beckett, a physicist who figured out how to travel within his own lifetime. But what made the series unique is that Sam wouldn't travel in his current body: his consciousness would leap into someone else's body during his timeline to change something in their life that was wrong. And once Sam solved the problem, he'd leap again to fix another issue for someone else.

This led Sam to becoming one of the most important time travelers in history: not only did he prevent Jacqueline Kennedy from getting assassinated with JFK, but he also set the stage for what eventually led to the discovery of the Watergate scandal. He also made important strides for seemingly ordinary people, giving them second chances they never had.

Quantum Leap aired for five seasons, and by the time the series ended, Sam went through lifetimes of experiences.

Continuum

Streaming On: Netflix

Continuum is a Canadian TV series that ended up on Syfy in the United States. The series follows a police officer from the future, Kara Cameron, who gets thrown back into our modern world after pursuing a group of terrorists. In our time, Kara learns that her future is far from perfect, thanks to corporations that are now the country's government, and must decide if she wants to save just herself or the world.

Continuum works as a time travel science fiction series, but also as a police procedural: Kara becomes involved with the investigation of the local police department that are hunting down the same people she is, and befriends the boy that will eventually become the man who made sure she traveled to the past.

Continuum ran for four seasons and unlike many shows, it got an actual finale, so don't worry about watching something that will leave you hanging at the end.