Hwang In-yeop (Korean: 황인엽; born on January 19, 1991) is a South Korean actor and model. He is known for his roles in dramas such as Why, Freshman, The Tale of Nokdu, 18 Again, and True Beauty. He made his acting debut in 2018 with lead roles in web drama Why and Freshman in 2019. He was also praised for his acting in The Tale of Nokdu as Park Dan-ho. He gained further recognition during his performance as Goo Ja-sung, a basketball captain who bullies Lee Do-hyun's son in 18 Again.

Hwang In-yeop plays as Gong Chan in Why Her?.
Hwang In-yeop is the top #1 member of the cast and appears in 16 episodes.

Heo Joon-ho (허준호) is a South Korean actor.  He was born on April 14, 1964. His father was actor Heo Jang-kang.

Heo Joon-ho plays as Choi Tae-guk in Why Her?.
Heo Joon-ho is the top #2 member of the cast and appears in 16 episodes.

Seo Hyun-jin plays as Oh Soo-jae in Why Her?.
Seo Hyun-jin is the top #3 member of the cast and appears in 16 episodes.

Bae In Hyuk is a South Korean actor who made his acting debut in 2019 with the short web movie "Love Buzz". He is currently managed under the actor agency Fides Spatium. In addition to his roles in the web series, he has appeared in two music videos.

Bae In-hyuk plays as Choi Yoon-sang in Why Her?.
Bae In-hyuk is the top #4 member of the cast and appears in 16 episodes.

Lee Jin Hyuk (Born: Lee Sung Jun), formerly known by his stage name Wei, is the main rapper, high rapper, and second to last member of the boy group UP10TION under company TOP Media. Before joining the group, he was worked as an actor and appeared in many commercial films. After training for seven years and two months, he made his appearance as a contestant on boy group survival reality show Produce X 101. He did not make into the debut 11, and was ranked the 14th position on Episode 12.

Lee Jin-hyuk plays as Nam Chun-poong in Why Her?.
Lee Jin-hyuk is the top #5 member of the cast and appears in 16 episodes.

Lee Joo Woo is a South Korean actress. She is known for her supporting role in the MBC's television series Return of Fortunate Bok (2017), which earned her an MBC Drama Award nomination.

Lee Joo-woo plays as Song Mi-rim in Why Her?.
Lee Joo-woo is the top #6 member of the cast and appears in 16 episodes.

Lee Kyu-sung plays as So Hyung-chil in Why Her?.
Lee Kyu-sung is the top #7 member of the cast and appears in 16 episodes.

Lee Kyung-young (이경영) is a South Korean actor. He was born on December 12, 1960.

Lee Kyung-young plays as Han Sung-bum in Why Her?.
Lee Kyung-young is the top #8 member of the cast and appears in 16 episodes.

Bae Hae Sun is a South Korean actress. She made her debut as an actress in 2002. Since her debut, she has appeared in several films and television dramas including, “Judge vs. Judge” (2017), “A Pledge to God” (2018), and “On Your Wedding Day” (2018).

Bae Hae-sun plays as Ji Soon-ok in Why Her?.
Bae Hae-sun is the top #9 member of the cast and appears in 16 episodes.

Jeon Jin-gi plays as Ha Il-goo in Why Her?.
Jeon Jin-gi is the top #10 member of the cast and appears in 16 episodes.