Supernatural officially became the longest-running horror television series of all time. The series just wrapped its 14th season and it will return for its 15th (and final) season in the fall of 2019. Given the longevity of the series, it's a given there would be some episodes that are much worse than others.
You don't write more than three hundred episodes without producing a few duds along the way. Many people have their opinions about which episodes are the "worst" Supernatural episodes of all time but this list highlights the bottom of the bottom. Check out the lowest-rated Supernatural episodes of all time according to IMDb.
10 10x13 - Halt and Catch Fire
Like with many other season ten episodes (season ten makes up the bulk of this list), "Halt and Catch Fire" is a "meh" kind of episode. It's not terrible but it's not memorable either. It's a blatant filler episode with overt parallels to the famous 90s film, I Know What You Did Last Summer.
The other issue with this episode is that every concept in it has been done before. It deals with a ghost on the internet, for one thing. There's a Ghost Whisperer episode with that same concept, and several horror movies that tackle the "death by technology" idea in a much better way.
9 9x15 - #thinman
"#thinman" is ranked as one of the top ten worst episodes of Supernatural according to IMDb because it was disappointing and full of lost potential. When the idea of Supernatural tackling its own version of the Slender Man legend was first proposed it made people super excited. Given the popularity of Slender Man, it's not surprising that people would find it perfect fodder for a Supernatural episode.
Unfortunately, the resulting episode was boring and didn't present anything to the "#thinman" story that was worthwhile. It was fun to have the Ghostfacers back for a while but it would have been better if the Thinman legend didn't wrap up with such a boring ending.
8 1x13 - Route 666
This is the infamous season one episode about a racist truck. Yes, seriously, a racist truck. Because this was a first season episode, like "Bugs," it can be somewhat excused. The first half of season one was a little rocky as the series tried to navigate its monster of the week format with its greater mythology arc and it gave us weird episodes like this one.
"Route 666" makes you think the writer's room was running dry on ideas and really scraping the bottom of the barrel. It's pretty surprising this episode didn't rank lower but again, I assume there is some forgiveness for how early in the run this episode premiered. Right now it has a 7.6 on IMDb.
7 10x16 - Paint It Black
The weirdest thing about the season ten episode "Paint it Black" is the strong amount of religious reverence. For a show that typically disavows all things religion (or frequently speaks about the Devil) this episode had a strangely strong component of Catholicism. "Paint It Black" featured an ancient ghost that was a little trickier to kill than usual.
It wasn't an all-out awful episode but it wasn't anything special either. Perhaps one of the best scenes is Dean's confession, which again, seemed a little strange, but Jensen Ackles was excellent during it. Right now the episode is rated with a 7.5 on IMDb.
6 10x21 - Dark Dynasty
This episode is not only one of the worst in Supernatural history but it might be one of the most controversial episodes because of what happens to a certain beloved character. Felicia Day, who played Charlie on the series, quickly became a fan favorite. She was one of the first openly gay characters introduced to Supernatural, which made her death particularly brutal.
The backlash to Charlie's death was intense... enough so that it got brought up at several fan conventions. The problem is, her death was lazy and unnecessary. Beyond her death, the episode featured more of the Styne family, Crowley, and Rowena, but Charlie's final scene is easily the most shocking and memorable from "Dark Dynasty."
5 10x04 - Paper Moon
For some reason, Supernatural has had a problem trying to make a good episode about werewolves. Many of their episodes featuring werewolves fall flat. "Paper Moon" is yet another example of that. It follows up on Kate, the werewolf Sam and Dean let live from the season eight episode, "Bitten."
In this episode, the brothers find a string of werewolf attacks going on and it leads them to Kate, but not everything is what it appears to be. This episode is clearly filler and it doesn't offer anything new or exciting. It's not particularly bad but it's forgettable. It sits at a 7.4 rating on IMDb.
4 8x04 - Bitten
Supernatural has done found footage episodes to varying degrees of success. "Bitten" was an attempt to follow up on the success of the many episodes featuring the Ghostfacers, which were well-done and performed to tons of fan love. Unfortunately, "Bitten" fell flat and thus landed it as one of the lowest-rated episodes of the show.
The problem with the format of some of the found footage episodes is they often don't feature much of Sam and Dean, who are the main reason fans watch the show. Sometimes the episode can still be interesting and carry on without them, but "Bitten" doesn't have an interesting enough story to manage that.
3 12x21 - There's Something About Mary
"There's Something About Mary" is the twenty-first episode of the 12th season of Supernatural. It follows Sam and Dean trying to figure out why hunters are dying all over the country due to mysterious "accidents." One of the reasons this is the third-lowest rated episode of Supernatural is because it features the death of yet another female character in Eileen.
The episode also has Mary losing her mind. Overall, it was poorly written and failed to have as much impact as an episode airing towards the end of the season should. People on Twitter even made a hashtag about the writers, calling for them to get fired. At present, the episode has a rating of 7.1 on IMDb.
2 1x08 - Bugs
This season one episode is famous for being one of the most hated out of the 300-plus episodes of Supernatural. The issue with "Bugs" is that one, people don't like bugs much and two, the episode really wasn't scary. Then you add in the issue of an Indian burial ground, which is a touchy subject these days, and you have an episode that really didn't age well.
Not only that but Sam and Dean don't actually manage to "defeat" anything in this episode. All they do is wait out the storm when the bugs come to attack. There isn't much closure.
1 9x20 - Bloodlines
The lowest rated episode of Supernatural across all of the seasons is the season nine episode, "Bloodlines." If you're a true-blue Supernatural fan then this probably doesn't surprise you. The episode was panned by critics and audiences alike when it premiered. It was meant to serve as a backdoor pilot for a new Supernatural spin-off series titled Supernatural: Bloodlines.
The series would follow a mafia-style group of supernatural beings such as werewolves and other monsters, in Chicago. Unfortunately, the premise was too similar to The Originals but not executed half as well and the concept was buried and canceled. It has a 6.0 rating on IMDb.