Of all the villains to feature in The Vampire Diaries, Katherine Pierce is probably the most popular and the most notorious. She has managed to hurt almost every single main character on the show during the course of eight seasons, which is a testament to her villainy.
Katherine began life on the show as series protagonist Elena Gilbert's ancestor and doppelgänger. She set out to destroy Elena's life, and everyone in it, and she was incredibly cunning and manipulative. However, even someone as scheming as Katherine can make mistakes.
Katherine Didn't Value Her Family
Way back when, before even Stefan and Damon Salvatore were born, Katherine found herself pregnant at the tender age of 17. Her daughter was born out of wedlock, and so her family made Katherine get rid of the child, and she never really searched for her daughter.
Katherine was banished to England where she met Klaus. Klaus wanted to use her to free his werewolf side, but Katherine sabotaged his plans. As a result, Klaus murdered Katherine's family. This was very distressing for her, but they were just collateral damage in her spat with Klaus.
Katherine Got On The Wrong Side Of Klaus
As one of the Original vampire family, Klaus was not someone you wanted angry at you. Klaus was the first vampire/wolf hybrid, and such, he was incredibly powerful. He was also incredibly nasty, vicious, petulant and downright scary at times.
Life is all about picking and choosing your battles. Katherine always looked out for herself but this meant getting on the wrong side of Klaus. Due to the hybrid's stubbornness and penchant for revenge, Katherine ruining his ritual was one mistake that she should never have made.
Katherine Slept With Damon And Stefan
There is absolutely nothing wrong with having a bit of fun. The Vampire Diaries as a show certainly doesn't shy away from portraying sex as something good and positive, which is fair enough, as it's mainly aimed at a teenage audience.
However, there is something slightly disturbing about sleeping with two brothers simultaneously. While both Damon and Stefan knew about the other, it was Katherine who seduced them. Unfortunately, her tryst with the Salvatores ended up turning them both against her later on.
Katherine Trusted Her Exes
A lot of relationships are wonderful at the beginning but some do go wrong pretty quickly. This all leads to the inevitable heartbreak of splitting up and going your separate ways. However, because this is The Vampire Diaries, it's not quite as simple as that.
For Katherine, her most prominent exes were Damon and Stefan. She enjoyed both of them tremendously, and they her, but eventually the siblings realized that they were just pawns in Katherine's game. Therefore, when she came to them asking for their help, it wasn't long before they betrayed her.
Katherine Pretended To Be Someone She Wasn't
This may be quite a twisted entry on this list but it is still a valid life lesson. There's no point in pretending to be someone other than who you actually are because you're not being true to yourself and so it can only end badly.
Katherine learned this lesson quite literally when she possessed Elena in Season 5, in a bid to keep herself from dying. In all fairness, it did work for a while but Katherine pushed it too far and eventually people realized that she wasn't Elena.
Katherine Occasionally Acted Without Thinking
Katherine was The Vampire Diaries' best antagonist for good reason. She was extremely entertaining to watch, her dialogue was sparkling with wit and she didn't take any prisoners, literally and figuratively. She was also one of the most cunning vampires on the show.
However, she did let emotion get the better of her on occasion, and it was then that she would react impulsively. For example, when she was trying to win back Stefan in the Season 2 premiere, she stabbed him after he told her unequivocally that he hated her.
Katherine Manipulated Those Around Her
Katherine was a master manipulator through and through. Before the events of the first season even occurred, she manipulated the Salvatore brothers and succeeded in turning them against each other. This started off their whole sibling rivalry that would become a theme for the show's run.
However, all this manipulation would eventually become Katherine's biggest mistake. It's fair to say that she really wasn't very popular with any of the characters and as such, she didn't have anyone to turn to when she really was dying.
Katherine Killed Jeremy
The one person who Elena loved more than Stefan or Damon was her brother, Jeremy Gilbert. The two were very close to each other, which made poor Jeremy a very tempting target for Katherine.
In Season 4, the hunt was on to find the miraculous vampire cure, which would turn any vampire into a human again. The main cast tracked the cure down but also found a sleeping Silas, the first doppelgänger. To wake him, Katherine needed human blood, and so she used Jeremy. This act of evil turned everyone against her.
Katherine Was Jealous Of Elena
Jealousy is never an attractive quality and it usually brings out the worst in people. From the moment Katherine first appeared in the present day, she made it her life's ambition to win back Stefan. The fact that he was currently dating Elena made no difference.
Katherine was jealous of Elena because Stefan loved her in a way that he had never loved Katherine. However, this was Katherine's own fault because she never gave love a chance over self-preservation. Katherine's jealousy ultimately led to her demise.
Katherine Put Herself Above Everyone Else
The one defining characteristic of Katherine Pierce is that she is extraordinarily selfish. Even before she became a vampire, she put her own life ahead of everyone she knew. She tricked Rose and Trevor into turning her, not caring that they'd now be hunted down by Klaus forever.
Katherine never mellowed over the years either; if anything, she just got worse. She tricked Tyler and Mason into triggering their werewolf gene just so that she'd have something to sweeten the deal when she handed the moonstone over to Klaus to ensure her own survival. As a result, Katherine was all alone and friendless when she finally kicked the bucket.