To quote a well-versed Doctor on the subject, “Time is like a big ball of wibbly wobbly time-y wimey…stuff.” Time can be fluid or rigidly fixed, and attempts to meddle in it have mixed results. This can also be said of shows that have time travel episodes or plotlines; it’s a tricky story to tell correctly. Many shows flounder when it comes to time travel stories.

Other shows have managed to write solid, consistent stories. Here are 5 shows that pulled off time travel stories, and 5 that didn't.

Did it Right: Fringe

This FOX show covered pretty much every story that science fiction has to tell. From parallel universes to shapeshifters, the show tackled a variety of tropes and stories.

Fringe introduced time travel via the Observers, a group of bald men in suits who appear at important historical events It's eventually revealed that the Observers are a genetically engineered species from the future, and are looking to recolonize and subjugate humanity. The show's final season dealt with the Fringe team undoing the Observers meddling and returning back to their original timeline. It was a cohesive story that resulted in a heart-wrenchingly beautiful finale.

Did it Wrong: Time After Time

Not even Cyndi Lauper could save this 2017 ABC show, which aired 5 episodes. The show starred writer H.G. Wells (Freddie Stroma), who had built the infamous time machine featured in his book. Said time machine is then stolen by Jack the Ripper, who transports into 2017 New York to continue his murderous rampage.

The series was muddled with poor pacing, as well as little use of the actual time machine. While a good concept, the show relied too much on the idea of historical figures using a time machine. Little effort was put into building up the characters and the world, and instead assumed audiences would be on board. Time travel should feel like an adventure and, instead, it felt like a long car ride with people you didn't like all that much.

Did it Right: Timeless

Abigail Spencer Malcolm Barrett and Matt Lanter Timeless Series Finale

NBC’s two season drama had a set of solid rules in place that made time travel believable and fun (even if the finale was forced to break some of those rules in the name of wrapping up the story).

Timeless featured Lucy Preston (Abigail Spencer), a history professor who worked with Master Sergeant Wyatt Logan (Matt Lanter) and scientist Rufus Carlin (Malcolm Barrett) to fight off terrorists who had stolen a time machine, as well as a secret organization known as Rittenhouse. The trio would use a 3 person “life boat” time machine to chase after these individuals and try and stop them from ruining the timeline. The show featured amazing stories from American history and obscure historical figures. The show was as informational as it was entertaining to watch, and fans of the show will certainly miss the antics of the Time Team.

Did it Wrong: The Flash

Flash Finale Time Travel Explained

The Flash wasted no time showcasing the fact that he can vibrate so quickly that he can literally time travel. Doing so has had...less than positive outcomes. The main problem has been that the concept of time travel has been inconsistent. Villains like Reverse Flash can time travel with seemingly little negative effect, while Barry's attempts end in disaster.

Season 5 of the show has ramped up the ridiculousness by having Nora (Barry and Iris West's future daughter) living with them in the present day in an attempt to save her father. Barry created the Flashpoint timeline by doing the exact same thing to save his mother, which had devastating effects on his friends and family. Apparently, Team Flash still hasn't learned their lesson on time travel.

Did it Right: Agents of S.H.I.E.L.D.

Characters from Agents of S.H.I.E.L.D. have fought off Inhumans, aliens, evil terrorists, and killer robots. It seemed like they couldn't go further in their ability to save the world.

Well, they could. Season 5 picked up immediately from the end of season 4, with the team abducted by a mysterious group and thrust into the future. In this future, Earth has been destroyed. Humanities survivors are slaves on a large space facility operated by the Kree. The team was forced to fight the Kree, save this future humanity, and find a way to their own timeline to stop it from ever happening. Themes like predestination and free will played back and forth, with each decision the team made inadvertently bringing them one step closer to causing the end of the world. It was a tense, thrilling season of television that set up the stakes like never before.

Did it Wrong: Legends of Tomorrow

Over time, so many side characters were introduced on Flash and Arrow that it made sense to put them all on one spin-off show. Thus, Legends of Tomorrow was born. Featuring heroes and villains alike, the Legends travel through time to protect the timeline.

While the show has a large following, it has gained a large share of detractors as well. Many take aim at the alarming frequency in how time travel rules are made and broken. Early on, the team is told that even the slightest change in the timeline can have huge consequences and that you only get one opportunity to fix things. Yet season 4 features John Constantine (Matt Ryan) rewriting the timeline however he likes, and the team is given opportunity after opportunity to fix it. While it's natural for shows to bend or break rules, shows like Legends lose their credibility when they do so. If the rules of time travel aren't considered sacred, then nothing else is.

Did it Right: Outlander

Outlander is the best show that no one is watching. The Starz production features WW2 nurse Claire (Caitriona Balfe), who while on holiday in Scotland comes across magical standing stones that transport her back to 1783. While there, she joins a group of rebel Scottish Highlanders, falls in love with the impeccably handsome Jamie Fraser (Sam Heughan) and attempts to figure out how to get back home.

It's rare that we get a time travel story that has its roots in fantasy, which is part of what makes this series a welcome addition. Outlander lives and breathes in the different time periods and locations the show takes us on. American audiences can learn a great deal about British history from the 1700s that doesn't necessarily have to do with the Revolutionary War, and the way Outlander treats issues of race and gender throughout different time periods is masterfully done. The show is smart, sexy, and manages to make time travel feel magical.

Did it Wrong: Lost

Henry Ian Cusick as Desmond in Lost

Lost got to work right away piling question after question on its audience. With years of anticipation building up, it should be expected that the series finale fell short for many people. The finale revealed that while the events of the show HAPPENED, but that they were also part of a dream. Yeah, we still don't really understand.

Time travel manifested itself in a number of ways. Desmond (Henry Ian Cusick) was seemingly able to travel using his memories. The island itself served as a vehicle for time travel, bringing its inhabitants to various time periods. However, the revelation that the island was a sort of limbo made many fans question how much of it even happened. The time travel episodes were well received at the time, but have not aged well given these questions.

Did it Right: Star Trek: The Next Generation

14 old picard

Star Trek is no stranger to time travel stories. The Next Generation encounters time travel in the form of aliens, ships, technology, and a demigod known as Q (John de Lancie). Each time, science and rationale give a clear reason for time travel existing and time travels effects feel consistent.

To many, the best use is in the series finale "All Good Things...". Picard finds himself traveling through the past, present, and future as part of the continuing trial of humanity brought forth by Q in the pilot episode. The show demonstrated how far the crew had come, as well as what awaits them in their future. The story was so well received that it earned the show an Emmy and the Hugo Award.

Did it Wrong: Life on Mars (US)

Life on Mars US Cast

If someone were to teach a masterclass on how to not adapt a BBC show, Life on Mars would be taught on day one. The show features Detective Sam Tyler (Jason O'Mara) who gets into a car crash in 2008 and awakens in 1973. A man out of time, Sam uses his future knowledge of police procedure to solve crime while also trying to find a way back home.

The US show took several liberties from its BBC counterpart.  This included a completely changed St. Elsewhere-esque ending. Sam was not living in 1973, nor was he a detective, but he was an astronaut. The AI had malfunctioned on his journey to Mars. Everyone he had imagined in the simulation represented his fellow crewmembers. It was a disappointment to fans, and there are more than a few who wished they could go back in time to change it.

NEXT: Star Trek Theory: Discovery’s Red Angel Is Next Generation's Space God