Even the best TV shows are not immune to having bad characters.

The existence of these characters isn't enough to ruin a TV show, but they are a blemish on an otherwise amazing series. Devoted fans who are committed to watching every episode of a show hate these awful characters. And when these people play major roles, they can be a real thorn in the sides of viewers.

These people might be annoying to the audience or their fellow characters (or both). The writing could also be at fault. They may be weak and underdeveloped. Perhaps we just don't care about them and their storyline and we get frustrated whenever they take up screen time. Sometimes it's clear that the writers have no idea what to do with this person and we long for them to be killed or otherwise written off. Other times, the performers just aren't capable of carrying off the character as written. And sometimes, they're terrible people. They commit horrible deeds or are just plain douchebags.

The characters on this list aren't all leads, but all play huge roles on their respective shows. Here are the 15 Worst Characters On Great TV Shows.

15. Dawn Summers (Michelle Trachtenberg) - Buffy the Vampire Slayer

Fans are always going to resist a character introduced many seasons into a show. That character really has to justify their presence on the show and be compelling right off the bat, or else every time you see them on screen you'll think "Ugh, why are they here?"

That was literally hte case with Dawn, who was introduced five seasons in to Buffy the Vampire Slayer, as if she'd been in the show all along. What's worse is that she's Buffy's little sister, set up as someone Buffy needed to protect. Not only is she a burden, she is really annoying. She is always making stupid decisions that get her into dangerous situations, and she forever needs to be saved by the Scooby gang. Oh, and she makes out with a vampire, as if she hasn't learned a single thing from Buffy's many romantic misadventures.

14. Wesley Crusher (Wil Wheaton) - Star Trek: The Next Generation

Think of every annoying teen you've ever met. Now think of Wesley Crusher. Wesley Crusher is worse. The problem is, Star Trek fans were predisposed not to like seeing a younger character on Star Trek: The Next Generation. The original didn't have any kids. Who wants a 15 year old genius hanging around the Enterprise, acting superior and outsmarting everyone? Even Wil Wheaton its Wesley was annoying.

Whenever Wesley would have a major episode, his storylines were super boring. Any fan would be forgiven for hoping Wesley would die somehow. Eventually, the writers realized Wesley was too awful to have on the show anymore and they wrote him out in season 4. No one missed him, not even his own mother, Beverly Crusher. "Shut up, Wesley." - Always and forever.

13. Marie Schrader (Betsy Brandt) - Breaking Bad

Skylar's sister Marie Schrader is extremely neurotic and worries constantly, and this quickly gets annoying for viewers to watch. She never stops babbling on about one thing or another. She's also pretentious, although it's not clear why, because she's not that great. And, oh yeah, she's a kleptomaniac! Marie, can you not? There are so many more important things going on on this show than your constant fretting.

Perhaps the worst thing she has ever done is telling Walt to kill himself. How can you say that to another person and live with yourself? The writers should have given her character more of a reason for existing. Not only would Breaking Bad have worked without her in it at all, it would have been better off.

12. Laoghaire MacKenzie (Nell Hudson) -  Outlander

Laoghaire is a despicable, scheming girl who tries to break up Jamie and Claire on Outlander. How could you not hate her?

Laoghaire, you are a teen. Claire is a woman. Step off. Also, Claire and Jamie are clearly meant to be together, so you can give up on your foolish attempts to steal him away from her. Laoghaire isn't just jealous, she's also a ruthless, evil person. She frames Claire for witchcraft and almost gets her burned at the stake.

Then in season 2 she comes back for one episode to give Claire and Jamie a phony apology for almost getting Claire killed. Unfortunately, we won't be seeing the last of Laoghaire: she's back for season 3 and book readers know she plays an important role.

11. Piper Chapman (Taylor Schilling) - Orange Is the New Black

From the second Piper Chapman enters Litchfield Penitentiary, she thinks she's above everyone else. She's a well-to-do New Yorker with a steady boyfriend. She thinks she's so much better than these criminals. According to Piper, her crime wasn't even that bad: she was part of a drug smuggling operation, but she didn't even handle the drugs, just the money.

Piper is a terrible person, obviously. But the fact that she's the main character is even worse. We are introduced to Litchfield through her perspective. That means we have to watch her whine, act like an innocent princess, and judge everyone.

The other characters on Orange is the New Black are so much more interesting than her (Taystee, Poussey, and Sophia, just to name a few), which makes spending so much time on her storylines is even more frustrating.

10. Daisy Mason (Sophie McShera) - Downton Abbey

Daisy is one of Downton Abbey's most boring characters. She mostly stays the same for the whole series; a mousey, shrill-voiced girl who toils away in the kitchen. She's always left out of any fun the younger staff is having.

With nothing going on in her love life, she creates crushes that she doesn't really have. The first time she does this, it had tragic results: she leads William on so much that he proposes to her and she accepts out of guilt. Then he is killed in World War I, leaving her a widow. She also formulates crushes on Alfred and Thomas, even though he's gay.

When she still doesn't have anything going in the love department by the final season, she convinces herself to settle for Andy. She literally looks at him doing manly construction work in his undershirt and goes "Eh, sure, I could marry him."

In season five, her character finally gets some motivation: she decides to better herself by learning math. However, the change was so abruptly written that it seemed to come out of thin air.

9. Hazel Wassername (Kristen Schaal) - 30 Rock

Jack Donaghy may have tried to tank NBC, but Kristen Schaal almost succeed in tanking 30 Rock. Her character was profoundly unfunny and a rare misfire for Tina Fey's critically acclaimed comedy goldmine. It didn't help that she was introduced in season 6, when reports were swirling that NBC was planning to end the show in season 7 (which it did) and 30 Rock needed the ratings more than ever.

Not only did none of her jokes land, Kristen Schaal's very pacing and energy were out of step with the rest of the 30 Rock cast.

Unfortunately for viewers, Kristen Schaal came back for season 7. Even her character's last name, Wassername, was uninspired. The show had already made that joke back in season four: Jenna's boyfriend Paul, played by Will Forte, has the surname is L'Astname.

8. Kirk Gleason (Sean Gunn) - Gilmore Girls

Kirk's annoying personality is supposed to be funny - and it is, in small doses. But too much Kirk in one small period of time makes Gilmore Girls fans tire of his antics.

Kirk, with his endless parade of random jobs, is the town clown of Stars Hollow. Although everyone else in town is a kooky character, Kirk is by far the most annoying. Everyone needs a Kirk break once in a while. But Stars Hollow is a small town, and it's impossible to avoid someone in a small town. So how have the citizens of Stars Hollow not chased him away with torches and pitchforks?

Sometimes, Kirk goes from being obnoxious to being a jerk - like when he drives a car into Luke's diner and doesn't even apologize.

7. Mark Brendanawicz (Paul Schneider) - Parks and Recreation

City planner Mark Brendana-quits... er... Brendanawicz (Paul Schneider) was a total nothing character. He epitomized nothingness. The show's writers created him and then clearly had no idea what to do with him. He's boring. He's a killjoy. He didn't make any impression in an otherwise strong ensemble cast. When we see that Leslie is infatuated with him, we can't help but wonder why.

Mark Brendanawicz hates his job, but he's apathetic about it, and about everything, really. Ron Swanson also hates his job, but in a way that made his character funny. Also, he clearly cares about some things: meat, woodworking, his coworkers (although he barely its it). Mark is just a downer.

Paul Schneider didn't fit in with the upbeat energy of the cast or the show. He was quietly written off after season two, and the penultimate episode of season two is when Rob Lowe and Adam Scott ed the cast, transitioning Parks and Rec into its Golden Age. Coincidence? No.

6. Emma Swan (Jennifer Morrison) - Once Upon a Time

At first, Emma Swan's purpose in Once Upon a Time is to be the person who doesn't believe what Henry tries to tell her: that everyone in Storybrooke is a fairy tale character, but because of a curse, they're left with no memory of their fairy tale life. Unfortunately, until things become more interesting for her character, Jennifer Morrison gives her only one emotion: disbelief. Early on, everyone else gets to be more interesting than her because we see them in Fairy Tale Land.

Let's be honest, the scenes in Fairy Tale Land are always better than the scenes in Storybrooke. So when we leave a scene full of princes, princesses, magic, and lavish costumes and production design for another scene of Emma in Storybrooke refusing to believe anything Henry tells her, it gets tiring.