Throughout his journey from villain to anti-hero, Klaus Mikaelson has made his fair share of mistakes on The Vampire Diaries and The Originals. What he considers mistakes are up for debate in his opinion, but his many friends and family know when he's really messed up.
Whether it's tearing someone's head off or breaking someone's heart, Klaus often acts out impulsively without thinking of the consequences. Even after a thousand years of living, he is still capable of making mistakes. For someone who brags about his immortal superiority, he sure shares a lot in common with humans.
Turned Tyler Into a Hybrid
Klaus chose Tyler Lockwood as his Guinea pig for creating a stable hybrid that wouldn't die. Little did he know what a pain in the side Tyler and his friends would become as the temperamental wolf fought to break the sire bond. It also put a permanent damper on Klaus' relationship with Caroline.
Although Caroline admitted she had an attraction to Klaus, she could never fully put her trust in him after what he did to Tyler. If he ever had a chance at Caroline's favor, he lost it.
Every Time He Daggered His Family
At the slightest annoyance or smallest act of betrayal, Klaus went into a fury and daggered his siblings to teach them a lesson. It was the paranormal equivalent of being put on time out. But not long after he always regretted the decision to put them in a coffin.
Many times he daggered them, he didn't realize one of his siblings held a vital piece of information he needed for his schemes. Other times, he knew the act would drive a wedge further between them.
Underestimated Freya
When the true eldest Mikaelson was resurrected and sought her family, Klaus had his reservations about her. He didn't believe she was really their sibling, and even when that proved true, he didn't trust her. But more than not trusting her, he underestimated her power.
Klaus thought at first Freya was just another run-of-the-mill witch that he could use when it suited him. But Freya proved more powerful and showed her brother a few times what she could really do if he got on her bad side.
Got Between Marcel and Rebekah
Rebekah fell in love with Klaus' adopted son, Marcel Gerard. But they kept their love affair a secret, as they knew how jealous Klaus was of his family. He only ever wanted everyone to love him above all others. They knew he would think their relationship a betrayal.
When Klaus realized they were together, he didn't break them up the way they thought he would. He resorted to crueler tactics and instead made them question each other's love for one another. Their relationship ended because Klaus played games with them.
Bit Caroline to Punish Tyler
After Elena and Jeremy kill Kol Mikaelson, they trick Klaus into a trap set by Bonnie, leaving him locked in the Gilbert house. Tyler comes to gloat and throw it all in his face, but Caroline shows more compassion, covering up Kol's body.
To punish Tyler, he grabs Caroline and bites her, knowing his werewolf venom is poisonous. Caroline lies for a long time dying before Klaus takes back his actions and cures her with his hybrid blood. He was able to reverse his rash behavior, but the emotional damage was done.
Lied About Who Killed Esther
Klaus was the only Mikaelson around when Esther died, so he was able to weave the lie that it was their father that did it. Knowing Mikael's cruelty, his siblings readily believed him. But the truth was, Klaus killed their mother, out of rage for suppressing his werewolf side.
Nearly a thousand years later, the truth came to light, and it changed his relationship with his siblings more than any other betrayal ever did. For the first time, they saw him as the monster Mikael always claimed him to be.
Rejected Jackson and Hayley's Union
Even though Hayley is in love with Elijah Mikaelson, she marries Jackson for the good of her pack to share her hybrid powers with them. But that's not why Klaus hates Jackson. He resents the bayou wolf for becoming part of their tight-knit family and playing the role of a father figure to his daughter Hope.
Jealousy leads him to make a terrible mistake in tearing Hayley and Jackson apart, and simultaneously away from Hope. His need to be loved and prioritized makes him steal Hope's mother from her.
Toyed With Aurora
When the original sired vampires return to their lives, Klaus thinks Aurora is still easy prey as she was when she was human. But the turn to a vampire amplified the psychological issues she already had and turned her into a merciless killer.
Aurora grows tired of being toyed with and learns that Klaus has true feelings for Cami O'Connell. To punish him for his cruelty, she kills Cami after the bartender drinks Klaus' blood to heal from her wounds. Aurora takes away the thing he loved most about Cami, her humanity.
Killed Greta's Husband
At the height of his days as a villain, Klaus killed a man right in front of his wife and children and left the family alive. That man turned out to be Greta's husband, a woman turned vampire that bided her time until she made her way back into the Mikaelsons' lives.
With his memory erased, Elijah fell in love with Greta's daughter and became part of their plan for vengeance on Klaus. Eventually, it all led to Hayley's death, and Hope lost her mother.
Cut Ties With Hope
While separated from his family to keep the Hollow away from Hope, Klaus returned to his old ways of killing for sport. One day Hope, eager to see her father, astral projected into a horrific scene as he fed on a man. Klaus screamed at her to go, and she never spoke to him again.
But it wasn't Hope that stopped their communication. It was Klaus. His shame at what his daughter saw led him to abandon her when all she wanted was an explanation.