Best monsters of all time

The "monster of the week" episode is an endangered beast. Once upon a time, television was full of single-episode stories, in which the heroes faced an unstoppable threat and won, all in about 43 minutes. Here are 10 "monster of the week" episodes that pack more storytelling power than a season-long arc of most TV shows.

Note: To help narrow things down, let's set a few conditions. We'll only include standalone "monster of the week" episodes where the monster in question appeared only once, and was never heard from again. So for example, Doctor Who's "Blink" is disqualified since it was arguably the first episode in a long-running arc involving the Weeping Angels. With that out of the way, here we go...

10 Terminator: The Sarah Connor Chronicles, "Self-Made Man"

When the Terminator TV show started, the creators said they wouldn't be doing "Terminator of the week" episodes — but then they did just one, featuring a random Terminator who goes back in time to kill a politician and overshoots, becoming Myron Stark, a big wheel in the 1920s gangster scene. Cameron, the friendly Terminator, figures out that Myron Stark is coming back, and manages to be there to greet him. It's a lovely, creative take on Terminator lore that uses time travel in a uniquely clever way.

9 Red Dwarf, "Polymorph"

It's sort of a weird version of Alien set on the Red Dwarf, in which the crew is hunted by a shape-shifting creature that steals their negative emotions to sustain itself. And it's often mentioned as one of the best Red Dwarf episodes, because the monster radically changes all of the characters and their dynamic winds up becoming very different before they deal with the monster. Often, the best monster-of-the-week episodes are the ones that change the regular characters in some way, or help us see them in a new light.

8 Cowboy Bebop, "Pierrot Le Fou"

This is the one where Spike gets his ass kicked, by a killer who targets him after Spike sees Pierrot commit a murder. Spike and his crew have to figure out who Pierrot is and what his weakness is, before he finishes the job. We discover that Pierrot is the result of strange experiments, which turned him into this abomination. This episode gets a lot of praise for its amazing visuals and intense atmosphere — but also for putting Spike in a position where he's already lost a fight at the beginning of the story, for once.

7 Xena, "A Day in the Life"

The monster this time around is the world's biggest giant, who's going to crush a village, and meanwhile some bandits are going to raid another village. But really, it's about exploring the Xena-Gabrielle relationship, while also introducing us to Minya, a young woman who feels threatened by Xena's awesomeness. In the course of the story, Xena has to outwit the bandits and giant while also empowering Minya — and the giant, whom we only meet this one time, is a particularly great foil in an episode about outsized personalities.