Lee Sung-min (Korean: 이성민; born October 15, 1968) is a South Korean actor. He first gained recognition for his supporting roles in television and film. He is best known for his performances in the series Golden Time (2012), Misaeng: Incomplete Life (2014), and Reborn Rich (2022), winning Best Actor at the Baeksang Arts Awards for the latter two works.

Lee has also received critical acclaim for his role in the espionage film The Spy Gone North (2018), for which he won several Best Actor awards. His other notable films include The Sheriff in Town (2017), The Witness (2018), The Man Standing Next (2020), and Handsome Guys (2024).

Lee Sung-min was born on October 15, 1968, in Dochon, a small village located between Bonghwa and Yeongju in North Gyeongsang Province. During his early years, his family frequently moved across the country, including Seoul and Gangwon, due to his father's relocations. He eventually returned to his hometown of Bonghwa in the fourth grade of elementary school, where he completed his middle and high school education. Afterward, he left Bonghwa again to pursue higher education at Daegu Science University.

Reflecting on his past, Lee credits his father for paving the way for his acting journey. His father, enjoyed watching movies with his son. Despite Bonghwa lacking movie theaters at the time, they frequently visited the two cinemas in nearby Yeongju. As valued customers, they would eagerly rush to see new releases. Lee recalls, "I still vividly recall the movies like King Kong and Bruce Lee that I watched with my father during my childhood." Lee further shared the significant impact of these early experiences: "When I was young, my father always ensured that I watched 'masterpiece films' on weekends. Thanks to him, I had the opportunity to experience cultural elements that were challenging for a rural child to access at such a young age. Perhaps, by absorbing movies through my father from an early stage, it enabled me to pursue an acting career and consistently engage in emotive performances."

He began his theater journey by becoming a part of the theater company Audience and Stage (객석과 무대) in Daegu. During this period, he had the opportunity to collaborate with esteemed colleagues, including directors Choi Joo-hwan and Jeong Cheol-won, both of whom had previously held positions as directors at the Daegu Municipal Theater Company. Reflecting on those days, Lee remarked, "Each troupe at the time pursued distinct directions, identities, and showcased different works."

While actively engaging in theater activities in Daegu, he swiftly gained recognition for his talent. Whenever he participated in various theater festivals, he effortlessly swept away awards. At the age of 24, he received the New Actor Award at the Daegu Theater Festival, an honor that can only be bestowed once in a lifetime. Additionally, he achieved the highest honor among actors in the Daegu region by winning the Daegu Theater Festival Best Actor Awards.

Lee crossed paths with his future wife in the play B Unso. She was the choreographer for the play. Their encounter marked a turning point in his life, as Lee went on to achieve remarkable milestones. In 2001, Lee joined the play produced by theater group Yeoninmudae (연인무대의) titled Pig Hunt. The play received the top prize (Presidential Award) at the 19th National Theater Festival, jointly organized by the Korea Arts and Culture Promotion Agency (Director Kim Jeong-ok) and the Korean Theater Association (Chairman Choi Jong-won). As a result, Pig Hunt received a prize of 20 million won and invited to the Seoul Performing Arts Festival held in October. The director of this work, Han Jeon-gi, and the lead actor, Lee Sung-min, received the Best Director Award and the Best Acting Award, respectively.

In 2002, despite being in his mid-thirties, Lee made a tough decision to leave his wife and daughter in Daegu and venture alone to Seoul. Determined to pursue a career as an actor, he yearned to test and validate his skills in Daehangno, the heart of the Korean theater industry. Encouragement from those around him further pushed him to embark on the journey to Seoul. At that time, Lee made a promise to his family, saying, "I will give it a try for three years, and if things don't work out, I will return."