K-drama fans have flocked to online boards to vent their displeasure at some of the most infuriating bad guys in recent memory.

With a number of characters generating heated debate regarding their smug grins, manipulative strategies, and seemingly bottomless capacity for dodging the law.

One fan, during the middle of the romantic drama Head Over Heels, said they felt immediate frustration whenever the female villain was on screen.

"That smug, fake smile of hers just makes me so frustrated. Like, I want her gone and leave Gyeon-U alone," the fan posted, adding that their criticism was of the character, not the actress, whose acting was widely acclaimed.

Others cited Su Min on Marry My Husband, who several called nauseating to behold during the latter part of the show.

"She's so disgusting that I felt like gagging... her smirk was so hard to look at," one commenter wrote.

Another wrote that watching the character in prison, still manipulating everyone around her, was "jaw-dropping."

During melodrama Buried Hearts, Yeom Jang Seon was compared to "mosquitoes at night" for his incessant whispering and plotting.

The fans were particularly frustrated with his timidity, which often enabled him to escape before he could face repercussions.

Villains in Queen of Tears likewise incurred anger for being arrogant, and some users took issue with the whole cast playing "villains" in their own right.

In the meantime, The Devil Judge's villain was lambasted as having an annoying voice and clothes that didn't fit.

For some viewers, the annoyance these characters evoke is evidence of great acting. As one commenter put it:

"She isn't even scary, just plain annoying. And somehow, that's exactly why she works as a villain."