Good mysteries are hard to do well.
You have to play fair, giving the audience enough clues to figure out the truth but not so many clues that the answer is obvious.
Some TV mysteries were so well done that we kicked ourselves for not realizing the solution before it was revealed, and we're celebrating those mysteries today.
Ideally, all shows should have a bit of mystery, so some of the best ones are shows you wouldn't expect, such as cartoons or comedies.
Every genre of show can keep certain things secret, teasing viewers with clues so they think they know what's going on but have to tune in to find out if they're right.
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Please scroll down to check out our top nine mysteries. Some of these we solved ourselves, while others we couldn't believe we missed.
[NOTE: This list contains spoilers, as it reveals the solutions to mysteries, so keep that in mind if you haven't watched all the shows on our list.]
1. The Identity of the Mother - How I Met Your Mother
Although How I Met Your Mother is often associated with Neil Patrick Harris's Barney, the show's premise rested on a season-long mystery: who was the mother the main character told his kids about?
The Mother, eventually revealed to be named Tracy, was hinted at as early as the first season, with what seemed to be a joke about Ted meeting a stripper named Tracy.
Clues were sprinkled throughout the remaining seasons, most famously when Ted spent a lot of time with the Mother's roommate, Cindy, who was constantly jealous of her roommate.
After the series ended, fans were outraged by the Mother's random death, which meant that Ted and Robin could get together rather than the Mother turning out to be any of the main characters.
Nevertheless, there were enough clues that sharp-eyed viewers could have figured out this plot twist before the end.
2. Who Rose Quartz Really Was - Steven Universe
Steven Universe was a quirky Cartoon Network series about a boy who lives with the Crystal Gems, mineral aliens with magical powers, and whom he helps on various adventures.
Throughout the series, Steven learns more about the Crystal Gems and that the alien race has a questionable past. He has to solve various mysteries along the way, one of which involves the identity of Rose Quartz.
Rose Quartz is a Crystal Gem originally introduced as a leader who led a successful rebellion against the Gem Empire.
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Throughout the series, Steven learns more about the war between the Crystal Gems and the Empire, including that his mother was assassinated by someone named Pink Diamond -- who turns out to still be alive and, in fact, is Rose.
Rose was often depicted as a nonconformist who strongly believed in making one's fate rather than accepting the identity given to one. She often dressed in pink, which was another clue to her identity.
3. Who Killed Laura Palmer? - Twin Peaks
Thirty years before the Showtime reboot, Twin Peaks was a quirky series about a small town full of secrets. It revolved around the mystery of who killed local teenager Laura Palmer.
The series combined standard clues with supernatural and other strange happenings throughout the first season and a half.
This should have tipped viewers off that the solution to the mystery would be anything but traditional!
One early sequence had Laura's father, Leland, develop a head full of white hair overnight, suggesting something was wrong with him.
This foreshadowed the idea that Leland was possessed by BOB, an evil entity that drove him to kill his daughter in a fit of rage.
4. Henry Thorpe Is the Main Antagonist - Sugar
Jason Butler Hamber's presence might have given away his character's true identity for some viewers. This actor is gifted at playing seemingly lovely guys who turn out to be evil.
Henry Thorpe was precisely that kind of character on Sugar.
He seemed incapable of hurting anyone, first appearing at Ruby's party and seeming so timid and inconsequential that almost nobody noticed him.
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Throughout the season, however, Henry became increasingly consequential to the story.
By the end, the reveal that he was an alien who tortured human women as part of sinister experiments is both shocking and completely logical.
5. Crowley's True Intentions - Rabbit Hole
Jason Butler Hamber also appears on Paramount+'s Rabbit Hole, a one-season series in which Kiefer Sutherland plays an espionage agent framed for murder, but he's not the main villain.
He again plays a guy who seems to be a good guy but is helping Crowley, the main antagonist.
Crowley's evil intentions were again more apparent in retrospect than upon first viewing, especially for viewers familiar with Peter Weir, who played him.
Weir almost always plays a villain, so why should this character have been an exception, especially with a name like Crowley?
6. Patrick Lloyd is An Overly Obvious Villain -- Designated Survivor
I know Terry Serpico as Law & Order: SVU's Chief McGrath, who recently resigned after years of being an annoying department head.
However, he also played the villain in the first season of Netflix's Designated Survivor.
Designated Survivor is, as the name implies, about the only survivor of a deadly attack on the Presidency ascending to the top position while trying to find the culprit.
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Serpico's character, Patrick Lloyd, was the CEO of a now-defunct military firm who would have had access to poison gas and a strong motive to kill the President.
This was a case of classic misdirection, in which the solution to the mystery was so obvious that viewers thought it couldn't possibly be correct.
7. Lily Kane's Killer - Veronica Mars
The first season of Veronica Mars focused on the title character's search for answers after her best friend was murdered.
Lilly Kane's killer was played by Harry Hamlin, which was one major clue. Hamlin is best known for L.A. Law but often plays villains, and this role was no exception.
This season-long mystery included false leads and red herrings before revealing who killed Lilly and why.
Each episode contained enough clues that sharp-eyed viewers could figure out the mystery, even though it wasn't necessarily easy.
8. Who Susan Twist Was Playing - Doctor Who
The newest season of Doctor Who involved two mysteries, and one of them was more solvable than it seemed.
Throughout the eight-episode season, actress Susan Twist appeared in bit parts in each story.
Showrunner Russell T Davies purposely led viewers to believe she was playing the Doctor's granddaughter, Susan, only for it to be revealed that she was a vessel for Sutekh, the god of death who had last appeared 50 years earlier.
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This mystery was easier to solve if you were a long-time fan familiar with the original story, but there were references to Sutekh throughout the episodes.
Episode 7 also contained an anagram fakeout that also included the real answer. Susan Twist was revealed to be Susan Triad, and her company was Sue Tech, a homonym of Sutekh.
9. The Identity of the Erinsborough Poisoner - Neighbours
The Australian soap Neighbours recently offered a compelling mystery with a solution under our noses.
Ever since Dr. Gavin Bowman came to Erinsborough, he seemed shady and was soon revealed to be a serial sexual harasser who threatened Remi when she reported him to HR.
However, Holly's theory that Bowman was poisoning people so he could play the hero at the hospital and get out of trouble seemed like yet another wild speculation on her part, especially after she was wrong twice before and nearly got arrested for attacking a podcaster she thought did it.
Yet Holly was correct, and the clues added up once she laid them out for her friends, not that anyone listened to her.
Over to you, TV Fanatics.
Which TV mysteries have you solved lately?
Hit the comments and let us know!