Meredith is the main character in the show. She is a general surgeon. The show mainly follows her life from when she was a first day intern, until were they show her now as a world class surgeon. The show shows all of the intense tragedies that she had to endure and how her life was as a child and her family now.

Amelia is a world class neurosurgeon. She becomes a big part of the show after her first appearance later in season 3. She is known as a incredible surgeon who can help almost anyone, even what is thought to be impossible. She also has to endure many hardships from being a past addict, to loosing loved ones, having many unhealthy and failing relationships and much more.

Addison is a world class neonatal surgeon. She was also known as Shepherd whilst she was married to derek or "She Shepherd". She was known for being able to save many babies and pregnancies that almost anyone would never have been able to do. She also had to go through a lot in her life starting in her childhood all the way through adult hood dealing with her mental health and many other things.

Teddy is a world class cardiothoracic surgeon. She had to deal with the traumatic death of her first husband and then a complicated love life following that loss. She was also a soldier so she had to carry a lot of trauma and grief with her throughout her life. In later seasons she is now the chief of surgery of the whole hospital.

Miranda is another one of the most important characters. She is a top tier world class general surgeon. She is shown from the very beginning from leading the new interns around, to creating a family, becoming chief, and dealing with a lot of mental health struggles from stress leading to more complex things.

Christina was a part of the very first intern class shown on the show. She is now a renowned cardiothoracic surgeon running the Klausman Institute for Medical Research in Zurich, Switzerland. She is Meredith's person, he best friend, and when things got hard they always remembered to dance it out. She was always the top of her class and is not shown as often in later seasons after her move, but she also had a complicated history through love life and much more.