Science fiction is a genre with huge potential, and the sky's the limit for great premises and storylines. However, even the most promising sci-fi shows don't always stay the course, falling off in their last seasons when it is most crucial to maintain consistency.
These shows started off strong, even winning critical acclaim like in the case of Westworld and The Handmaiden's Tale. Unfortunately, they could not sustain the magic of earlier seasons, with stories becoming outlandish, or characters losing themselves in convoluted plots. The last seasons of these shows were their worst.
10 The 100
This post-apocalyptic show took place after a nuclear calamity had wiped out all of humanity and made the Earth uninhabitable. Years later, the surviving humans sent a faction of hundred juvenile delinquents to test whether the planet was worth returning to.
The 100 developed a cult fan base but disappointed most with the seventh and final season where the sci-fi show went off the rails. There was too much killing, resulting in the loss of many beloved main characters. The plot was overstretched and underdeveloped, and every character acted bizarrely throughout this season. Clarke killing Bellamy was a low point that made no sense at all.
9 The X-Files
At 11 seasons, The X-Files is one of the longest-running sci-fi shows of all time, focusing on conspiracy theorist Fox Mulder and his partner Dana Scully solving cases of extraterrestrial and supernatural nature. Sadly, the last season of the show became too caught up in the glory of its own conspiracies, resulting in nonsensical stories that irritated audiences.
This season of The X-Files also had a huge amount of clunky and cringeworthy dialogue that also turned audiences off. The last episode also felt rushed, thereby leaving too many loose plot threads that the final season couldn't solve.
8 Heroes
Heroes was loved unanimously when it first premiered, with a simple but sophisticated story about regular people who develop superhuman powers like regeneration, space-time manipulation, and flight. After a stellar first season, Heroes had set hopes high for audiences and critics alike, but the downward spiral had begun in the second season itself.
However, Heroes' last season was when fans expected the show to come back to its former glory, which did not happen. The villain was introduced too late, and the series was littered with continuity errors that made viewers believe that the crew wasn't even trying. Infuriatingly enough, the show ended on a cliffhanger before being canceled.
7 Alphas
SYFY's Alphas managed to last for two seasons but faced cancelation soon after due to declining audience figures. This show centered around a crew of superhumans with various abilities known as the Alphas that work within the government. Their job was to go after other rogue Alphas who commit crimes and bring them to justice.
Alphas' premise was gripping from the beginning and both seasons were a good watch, however, this sci-fi show ended on a cliffhanger so large that it did not sit well with audiences. In the last moments of the final season, a photic bomb went off at Grand Central station, resulting in the death of every human except for one Alpha, Gary. This massive unresolved plot left a bad taste.
6 Wayward Pines
Based on the trilogy of books of the same name, Wayward Pines was always supposed to be a limited series with a single season. The show originally followed Ethan, a U.S. Secret Service agent investigating two missing agents in the town. He wakes up from an accident and realizes that something is amiss about Wayward Pines, where people are punished with death for leaving.
The critical success of Wayward Pines led to a renewal, with a different showrunner and a largely new cast. The second and final season could not recreate the charisma of the first season and felt dull and repetitive. It did not get a third season.
5 Revolution
Eric Kripke hit the jackpot with Supernatural, but couldn't quite achieve even a fraction of its success with Revolution. It revolved around a dystopian world where the power went out, permanently, and humankind had regressed back to military leadership when the breakdown happened.
Season 1 itself was shaky, but fans expected Revolution season 2 to be stellar, to revive the show. This second and final installment changed a lot of the plot and villains from before, but the problems that the characters faced remained the same. There was no novelty, and the planned third season was also scrapped.
4 Lost
The Lost series finale continues to be one of the worst TV endings to date, as the last season nullified everything that the characters had gone through for five seasons prior. It was a watercooler show that everybody would watch keenly, as the tale of the plane crash survivors unfolded with more mystery than the previous episode.
Instead of tying up loose ends, Lost season 6 focused too much on an emotional ending and the filler Flash Sideways plot that made little sense. Riddled with plot holes, the last season deteriorated further when it was revealed that everything had just been the afterlife and that everyone had been dead the whole time.
3 Westworld
Many great sci-fi shows start off with a bang but are unable to sustain this beyond the early seasons. HBO's Westworld suffered greatly from this same syndrome, which was why season 4 couldn't redeem this story about a lavish theme park where the wealthy interact with androids and fulfill their fantasies.
Despite top-notch visuals and CGI, this season of Westworld flailed with illogical plots and character motivations that only existed for shock value. Below-average subplots took away from the main storyline, which was also weak and boring in many spots. Westworld may have returned to the park, but the journey was not a good one.
2 The Wilds
The premise of The Wilds wasn't novel, but the show added its own distinct touch to it which made it so bingeworthy. The teen girls who became unwitting test subjects in the Dawn of Eve project through a set-up plane crash were compelling, but the introduction of the boys in season 2 was not the best move.
Introducing the boys to The Wilds distracted from the main characters and plot and added little to the show. The attention of the audience was split in two different directions, even though the Dawn of Eve project had enough potential to float the show without a "brother" project being added.
1 ALF
This sci-fi sitcom was by no means a critical success, but it lasted four full seasons. ALF followed the titular alien who crash-landed in the Tanner family's backyard and thus began cohabiting with them. It was funny with a touch of sci-fi, but the last season took it to a dark place.
The final season of the show ended with ALF getting caught by the US military's Alien Task Force, after which the show ended. Fans had no idea whether he would be harmed or punished at the time by the military and ruined the funny sci-fi sitcom for good with the dark twist.