Lee Sung Jin

He is known for creating the Netflix series Beef, for which he received the 2023 Primetime Emmy Awards for directing and writing for a limited series.

Lee Sung Jin was born in South Korea in 1981. His family moved frequently in his youth; he moved to the United States when he was nine months old, and returned to Korea for third through fifth grade. He then relocated from Seoul to Minnesota, United States, in sixth grade. He also lived in Illinois, Louisiana, Iowa, and Texas. He recalls it being “a horrible time to have a name no one can pronounce" and chose to go by "Sonny" instead.

He attended the University of Pennsylvania, where he sang in an a cappella group. He graduated in 2003 with a degree in economics.

After he graduated from college, he worked a variety of part time jobs while writing scripts. He interned at the Sony record label Barsuk Records. He wrote for the series Undone, Tuca & Bertie, Dave, and Silicon Valley. In 2008, he worked as a screenwriter for It's Always Sunny in Philadelphia.

He was inspired to create Beef by a road rage confrontation he experienced with a middle-aged white man in Los Angeles. "I thought there was something interesting there, how we’re all locked in our subjective world views, and we go around projecting a lot on the other person and not really seeing things for what they are," he said of the incident. He also served as director, executive producer and showrunner on the series, forced to remotely direct scenes from the season finale "with my face on an iPad" because of a COVID-19 infection.

In August 2023, he visited South Korea to speak at a conference on the creation of films. During this, he said that he had not been back to South Korea since his childhood, for around 25 years.

In November 2023, Variety reported that Lee had signed a multiyear deal to produce content for Netflix.

Lee is the screenwriter for the 2025 Marvel Cinematic Universe film Thunderbolts*, which is his first credit for screenwriting on a produced film.

Lee lives in Los Angeles with his wife and three dogs. He plays the violin, guitar and piano.