Set against the turbulent backdrop of South Korea from the 1980s to the 1990s, the series depicts the story of three young people who fight fiercely to protect their dreams, friendship, and their one and only first love.[10][11]
Jang Dong-yoon as Lee Doo-hak: the son of a farmer in a quiet and small village in Yeosu. He is forced into the life of crime due to circumstances.[12]
Seol In-ah as Oh Jung-shin: an honest and confident woman who knows how to fight against injustice.[11]
Choo Young-woo as Choi Chul-woong: A prosecutor and Doo-hak's childhood friend-turned-rival who is an intelligent and competitive man. He is also secretly Doo-hak biological younger brother[13]
Jeon No-min as Hwang Chung-seong: a former brigadier general of the security forces and the current deputy director of the Agency for National Security Planning.[21]
Jin Yi-han as Oh Man-ok: Chung-seong's right-hand man.[21]
Park Won-sang as Choi Young-sik: Chul-woong's father and a rich millowner and former politician who represents the poors.[12]
Ha Hye-seung as Gyeong-ja: a maid who works at Chul-woong's house.[12]
^ abcHa Su-jeong (August 31, 2022). "장동윤·설인아·추영우, KBS2 클래식 멜로 '오아시스' 캐스팅 [공식]" [Jang Dong-yoon·Seol In-ah·Choo Young-woo, cast in KBS2 classic melodrama 'Oasis' [Official]] (in Korean). OSEN. Archived from the original on January 3, 2023. Retrieved January 3, 2023 – via Naver.
^"Oasis". KBS World. Archived from the original on July 2, 2023. Retrieved April 18, 2023.
^ abcAhn Yoon-ji (January 5, 2023). "도상우, KBS '오아시스' 합류..장동윤과 호흡[공식]" [Do Sang-woo joins KBS 'Oasis'.. Breathing with Jang Dong-yoon [Official]] (in Korean). Star News. Archived from the original on January 5, 2023. Retrieved January 5, 2023 – via Naver.
^Yang, Seung-mo (December 18, 2023). "래몽래인, 콘텐츠 제작 확대 기대감 '↑' [IBK투자증권]" [Raemongraein, Expectations for expansion of content production '↑' [IBK investment securities]]. Energy Economy Newspaper (in Korean). Retrieved January 5, 2024.
^Jang Woo-young (January 30, 2023). "'오아시스' 3월 6일 첫 방송…설인아에게 반한 장동윤 [공식]" ['Oasis' first broadcast on March 6th… Jang Dong-yoon fell in love with Seol In-ah [Official]] (in Korean). OSEN. Archived from the original on January 30, 2023. Retrieved January 30, 2023.
^Choi Ji-yoon (March 15, 2023). "이나영 복귀작 기대↑…웨이브, 상반기 알찬 라인업" (in Korean). Newsis. Archived from the original on March 21, 2023. Retrieved March 21, 2023 – via Naver.
^"Oasis". RaemongRaein. Archived from the original on January 3, 2023. Retrieved January 3, 2023.
^ abYoo Jung-min (August 31, 2022). "설인아, '오아시스' 출연 확정...청춘 멜로퀸 도전" (in Korean). Ten Asia. Archived from the original on January 3, 2023. Retrieved January 3, 2023 – via Naver.
^ abcdefghijklmnop"등장인물" [Characters]. KBS (in Korean). Archived from the original on February 22, 2023. Retrieved February 22, 2023.
^Lee Ho-young (February 27, 2023). "장동윤 아빠役" 김명수, '오아시스' 출연확정 [공식입장]" (in Korean). iMBC. Archived from the original on February 28, 2023. Retrieved February 28, 2023 – via Naver.
^Jang Woo-young (February 22, 2023). "소희정, 장동윤 母 된다…'오아시스' 출연 [공식]" (in Korean). OSEN. Archived from the original on February 22, 2023. Retrieved February 22, 2023 – via Naver.
^Yang So-young (March 8, 2023). "'오아시스' 장동윤, 추영우 대신 교도소行...설인아와 재회할까" ['Oasis' Jang Dong-yoon goes to prison instead of Choo Young-woo... Shall we reunite with Seol In-ah?] (in Korean). Maeil Business Daily. Archived from the original on March 8, 2023. Retrieved March 8, 2023 – via Naver.
^Lee Yoo-min (March 10, 2023). "이교엽 '오아시스' 출연…장동윤과 호흡" [Lee Lee Gyo-yeop appeared in 'Oasis'… Breathing with Jang Dong-yoon] (in Korean). Sports Kyunghyang. Archived from the original on March 10, 2023. Retrieved March 10, 2023 – via Naver.
^Hwang Soo-yeon (April 10, 2023). "정보민, 재벌집 막내딸 된다…'오아시스' 합류 [공식입장]" (in Korean). Xports News. Archived from the original on April 10, 2023. Retrieved April 10, 2023 – via Naver.