Before her global success on Killing Eve, Sandra Oh rose to fame on the hit medical series Grey's Anatomy. The two-time Golden Globe winner played cardiothoracic surgeon Cristina Yang, who was Meredith Grey's (Ellen Pompeo) best friend. Fans grew to love her ambitious and candid attitude, as it provided comic relief in the darkest of moments.

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Cristina became a world-renowned surgeon by the end. However, it did take a while for the character to get there. Fans are well aware of the hurdles she had to jump, ranging from Burke injury to almost killing Alex in the O.R.  Here are the top ten worst things Cristina has ever done.

She Disrespected Emma and Owen's relationship

Owen and Cristina smile while embracing in Grey's Anatomy

Cristina had a whirlwind romance with trauma surgeon Owen Hunt (Kevin McKidd). From season 5 to season 10, the couple had their ups and downs. From Owen's PTSD, Teddy's (Kim Raver) reappearance and Cristina's abortion, the pair didn't have the smoothest of relationships. The final nail in the coffin was when Cristina realized Owen still wanted to have children and she didn't.

Owen began seeing maternal-fetal surgeon Emma Marling (Marguerite Moreau) in season 10. Emma was the complete opposite of Yang; she had a warm attitude and wanted to have a family. Their relationship soon got serious when the pair planned to move-in together. That was until Owen decided to cheat on her with Cristina - who was fully aware of their relationship. It wasn't a nice moment for Yang.

She Nearly killed Alex

Alex Karev looking serious at the hospital on Grey's Anatomy

Everyone is aware of Cristina's love for surgery. Fans know it and the surgeons at Grey Sloan did too. In the episode "She's Gone", the attendings are on the lookout for the new Gunther. This was a nickname given to a doctor who took charge during the team-building exercise. Everyone, bar Teddy, bet it would be Yang.

However, the surgery proved it was Jackson after Cristina messed up. As Teddy expected, Cristina began to work too quickly and wasn't careful with the instruments. She ended up stabbing Alex (Justin Chambers) with a syringe full of epinephrine, which caused him to collapse. Yang ended up being a liability because she didn't take the time to think.

She Blamed Meredith for her PTSD

Cristina and Meredith at the hospital on Grey's Anatomy

Grey Sloan was never the same after the hospital's mass shooting. Many of the doctors had PTSD, including Cristina who quit the program. She tries to distract herself with wedding planning and bartending but eventually comes back to the hospital. The road to recovery was long as she had PTSD episode in "That's Me Trying".

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Cristina takes it all out on Meredith. "You were there with your sad eyes, screaming at me to save his life," she says. "I didn't have a choice and you did that. If it was anyone else standing there, I would've walked away. I wouldn't be here." It's a little harsh of Cristina to blame Meredith when her anger should be directed towards Gary Clark's (Michael O'Neill) vendetta.

She covered up for Preston's injury

Preston Burke gets reprimanded by Richard Webber

The end of season 2 saw Cristina's boyfriend, Preston Burke (Isaiah Washington), shot. The bullet had been lodged in his shoulder, which caused extensive nerve damage to his hand. Burke was unable to operate as he had a tremor. Cristina was the only one who knew about it so they came up with a plan to hide his condition.

Cristina was the mastermind behind the plan, scheduling and operating on Burke's surgeries. While supporting Preston, she also got access to rare procedures that began to raise suspicion amongst the other residents. Eventually, the pressure got to Cristina and she confessed all to Richard Webber (James Pickens, Jr). She did the right thing in the end, but they shouldn't have put his pride ahead of the patient's welfare.

She didn't report the intern cabal

Lexie and Sadie talking in the morgue in Grey's Anatomy

Cristina made the mistake again by not reporting the intern cabal. After the Denny Duquette (Jeffrey Dean Morgan) situation and Burke's injury, fans would think Cristina had learned her lessons. Whilst they cannot fault her loyalty, fans knew it would come back to bite her.

As the residents weren't teaching the interns, they decided to practice the procedures on themselves. This ranged from sutures, epidurals and attempting to remove an appendix. Cristina found out when Webber complimented Lexie (Chyler Leigh) on her skills and ordered them to stop. Although she did it with good intentions, Cristina should have told Webber before they put Sadie's (Melissa George) life at risk.

She was Unnecessarily rude to April

Cristina may have become quasi-friends with April (Sarah Drew), Lexie and George (T.R. Knight), but she was genuinely rude to them most of the time. She was even rude to the people she most cared about. But it was April who got the brunt of it.

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Fans will be able to remember April as the character departed the show two years ago. She was a trauma surgeon, who was loved by many because of her warm, optimistic attitude. Not once was she hostile towards Cristina, even when Yang continued to mock her with imitations and jibes. Fans couldn't help but feel for April sometimes, especially when she stood up to Teddy for her.

She took pleasure in people's injuries

Cristina and Izzie takes pictures with the patient who believed he was pregnant

On many occasions, Cristina has shown to have a poor bedside manner. Cristina was deemed a robot by the other doctors because of her lack of compassion. She would often take pleasure in patient's injuries and express her delight in their presence. She came across very insensitive.

A prime example of this is in "Something to Talk About", when Izzie (Katherine Heigl), Meredith and Cristina fight over a case. This involved a male patient believing he was pregnant. Cristina and Izzie decide to make money off the case, charging other doctors and nurses admission to stand in the room. It was uncomfortable to watch as they completely ignored the patient's wishes. It was completely wrong of her to publically embarrass the patient.

She mocked Burke's spiritual beliefs and traditions

They were a cute couple at the time, but the signs of impending doom were there. Burke and Cristina had nothing in common. Fans found this out in the episode "Grandma Got Run Over by a Reindeer" when Yang judged Burke for believing the body and spirit were connected. Cristina's thought his faith was in science so she was surprised by this admission. She crosses the line when she compares his spirituality to someone's belief in Santa Claus.

Cristina humiliates another person because she doesn't comprehend how her words can hurt. Just because she doesn't believe in any religion does not mean she should try and take it from others who do.

She Had A fight with Meredith

Cristina argues with Meredith over their conflicting interests

Cristina and Meredith are known to be like two peas in a pod. However, their friendship was strained in season 10 when the pair began to argue over their respective careers. Cristina began to excel in surgery whilst Meredith had taken a step back to adjust to motherhood. It was a simple discussion that took a wrong turn as Meredith began to believe Cristina thought she was better than her.

Cristina did not help matters as she betrayed Meredith in "Two Against One". Meredith was using a 3-D printer to print a model of a liver (for research). However, Yang ended up destroying the prototype so she could use the machine. It strained her relationship with Meredith further as it affected her research.

She Accused Meredith of getting into the program because of nepotism

Cristina and Meredith with George in the background talking to Bailey on Grey's Anatomy

Before they became the twisted sisters, Cristina viewed Meredith as her competition. In the pilot, fans see Meredith and Cristina pair up to work on the Katie Bryce case. They arranged a deal that would allow Yang to have the surgery. However, Meredith betrays her by accepting it instead.

Out of anger, Cristina lashes out at Meredith when she comes to apologize. "I don't get picked for surgeries because I slept with my boss and I didn't get into med school because I have a famous mother," she says. "Some of us have to earn what we get". It was unfair on Cristina's part to judge as Meredith was already struggling with her mother's legacy.

NEXT: Grey's Anatomy: 10 Things You Didn't Know About Meredith and Cristina's Friendship