Ghost Doctor

Lee Ji-woo/ Jessica.

Han Seung-won: in his mid 40's, Executive Director and Go Seung-tak's older cousin. He is a two-faced man with an invisible dagger inside, and the main villain.

Jang Min-ho: in his early 40's, son of Chairman Jang Myung-duk. He is a cold-hearted man who takes advantage of his father's illness to become the heir to the group.

Ban Tae-sik: in his early 50's, Chief of Thoracic Surgery. In front of other doctors, he shouts "I was a genius in my old days", but in front of Cha Young-min, he always gets smaller.

Go Seung-tak: 28 years old, 1st year thoracic surgery resident who is a "silver spoon" resident in the hospital, as his grandfather is the founder of the hospital, and his mother is the current chairman of the foundation. He has excellent theoretical knowledge but is practically clumsy at work.

Jang Se-jin: 38 years old, Cha Young-min's ex-girlfriend. She had to leave for overseas due to her father a decade ago without having the chance to explain to Cha Young-min. This made Young-min disappointed since he believed she left due to having found a rich father and she no longer cared for him. She is an overseas genius neurosurgeon and was raised by a single mother. Reconciled with Young-min in the end.

Oh Soo-jeong: 28 years old, a highly talented emergency room intern who is straightforward at work and wants to be a cardiothoracic surgeon. She is Go Seung-tak's best friend and love interest, and the granddaughter of Oh Joo-Myung, who becomes the ghost "Tes" after his death.

Tes/Oh Joo-myung: Oh Soo-jeong's grandfather. A genius and compassionate cardiothoracic surgeon before he died in his 60's. Twenty years after his death, he still wanders the hospital as a ghost, helping the patients by possessing the hospital staff, including Cha Young-min while in his residency.