While these celebrities solidified themselves as actors and actresses, many people seem to have forgotten (or never even knew!) that they started their careers in entertainment as idols. 

1. Park Hyung Sik

Park Hyung Sik first made his debut as an idol with the boy band ZE:A in 2010, and was subsequently added to the group's first sub-unit, ZE:A Five. He debuted as an actor in 2012, starring in the SBS drama "I Remember You."

Now, he is mostly known for his roles in "The Heirs" (2013), "High Society" (2015), "Hwarang: The Poet Warrior Youth" (2016), "Strong Woman Bong-soon" (2017), and "Suits" (2018). Park Hyun Sik not only acts in dramas but in movies and in theatre as well.

2. Kwon Nara

Kwon Nara's beginnings in the industry started in 2012, debuting with the girl group Hello Venus. She started her acting career that same year, appearing in a small cameo role as a stewardess in one of the episodes of SBS's "Take Care of Us, Captain."

She bagged her first major acting role in 2017 in the drama "Suspicious Partner." Since then, Kwon Nara has been focusing on acting. Some notable dramas she has starred in include "My Mister" (2018), "Your Honor" (2018), "Doctor Prisoner" (2019), and "Itaewon Class" (2020). She currently stars in the historical comedy "Royal Secret Agent."

3. Yook Sungjae

Yook Sungjae debuted as a member of BTOB in March 2012. He is also a member of the sub-unit BTOB Blue. Sungjae also debuted as a soloist in March 2020, two months before his military enlistment.

He made his debut as an actor in 2013 in the drama "Monstar" with a small supporting role. He achieved breakthrough success as an actor in 2015 in the teen drama "Who Are You: School 2015". He is now known for his roles in the dramas "The Village: Aciara's Secret" (2015), "Guardian: The Lonely and Great God" (2016), and "Mystic Pop-up Bar" (2020).

4. Kim Myungsoo

Kim Myungsoo entered the entertainment industry as a member of the boy group INFINITE under the stage name L in June 2010. He subsequently debuted in the group's sub-unit, INFINITE F. He left INFINITE's company, Woollim Entertainment, in August 2019, but is still a member of the group.

He debuted as an actor in 2011, appearing in the Japanese drama "Jiu Keishicho Tokushuhan Sousagakari." He made his first appearance in a South Korean series in 2012, acting in the tvN drama "Flower Band." He achieved breakthrough success as an actor in 2017 for starring in the historical drama "The Emperor: Owner of the Mask."

He is known for his roles in the dramas "My Catman" (2016), "The Day After We Broke Up" (2016), "Ms. Hammarubi" (2018), "Angel's Last Mission: Love" (2019)", and "Meow, the Secret Boy" (2020).

5. Seo In Guk

Seo In Guk's first appearance in the entertainment industry was as a contestant on the Mnet's singing content, "Superstar K," where he won the first season. Seo In Guk kickstarted his career as a soloist, releasing numerous chart-topping singles and albums.

Seo In Guk made his acting debut in 2012 in the KBS drama "Love Rain." He achieved breakthrough success that year with the leading role in tvN's "Reply 1997". He has since starred in numerous popular dramas such as "High Schol King of Savvy" (2014), "Hello Monster" (2015), "Squad 38" (2016), "Shopping King Louie" (2016), and "The Smile Has Left Your Eyes" (2018).

6. Lee Howon (Hoya)

The second INFINITE member on the list, Hoya debuted with the group in 2020 and subsequently debuted in the sub-unit INFINITE H. He left the group in 2017 after departing from Woollim Entertainment.

He made his acting debut in the tN drama "Reply 1997". The drama was a huge success and earned him massive success as an actor. He starred in his first film in 2014 in the film "Hiya." He is most known for his roles in the dramas "My Lovely Girl" (2014), "Mask" (2015), "Radiant Office" (2017), "Two Cops" (2017), and "Devilish Charm" (2018).

7. Lee Hyeri

Hyeri debuted as a member of Girl's Day in 2010 as a new member of the group. During her years as an active idol, she earned the nickname "Nation's Little Sister" after her appearance on "Real Men."

Hyeri made her debut as an actress in the SBS weekend drama "Tasty Life." She achieved breakthrough success in 2015 following her role "Reply 1998", in which she earned critical and audience acclaim. She is known for her roles in the drama "Two Dops" (2017) and "Miss Lee" (2018), as well as the films "Monstrum" (2017) and "My Punch-Drunk Boxer (2018).

8. Lee Joon

Before making a name for himself as an actor, he debuted as a member of the boy group MBLAQ. As a member of the group, he released three single albums, seven EPs, and one studio album. He left the group in October 2014. He debuted as a soloist in 2017.

He first debuted as an actor in 20120 in the youth drama "Jungle Fish 2". He earned fame in 2013 for his film "Rough Play," which garnered attention for being risque for a K-pop idol due to the numerous nude scenes. He is known for his roles in the dramas "Gap-dong" (201), "Mr. Back" (2014), "Heard it Through the Grapevine" (2015), "The Vampire Detective" (2016), "The Woman with a Suitcase" (2016) and "My Father is Strange" (2017).

9. Im Siwan

Im Siwan first made his debut in the nine-member boy group, ZE:A, in 2010. Before their floral debut, they went around South Korea to perform guerilla performances. Im Siwan is also a member of the sub-unit ZE:A Five.

Im Siwan debuted as an actor in 2012, playing the young version of Heo Yeom in the drama "Moon Embracing the Sun." The drama was praised as the "National Drama," launching Im Siwan to fame. He is known for his roles in the film "The Attorney" (2013) and the drama "Misaeng: Incomplete Life" (2014).

10. Jung Jinyoung

Jinyoung debuted as a member of B1A4 in 2011 under WM Entertainment. He is also active as a composer and producer, producing some of B1A4's work and composing songs for "Produce 101" and for some of the dramas he has starred in. Jinyong left WM Entertainment in June 2018 and is no longer promoting with the group.

Jung Jinyoung debuted as an actor in 2013, with a role in the tvN drama "She is Wow." He is known for his roles in the film "Miss Granny" (2013), and "The Dude in Me" (2019), as well as for his roles in the dramas "Love in the Moonlight" (2016), "If We Were a Season" (2017), "My First First Love" (2018) and "Wind-Bell" (2018),