Cast
Main
1. Lee Jong-suk as Kang Chul➡27
2. Han Hyo Joo as Oh Yeon-joo➡29
Hyun Seung-min as teenage Yeon-joo➡17
Park Min-ha as child Yeon-joo➡9
Characters from the webtoon W
3. Kim Eui-sung as Han Sang-hoon➡51
4. Jung Yoo-jin as Yoon So-hee[8]➡27
5. Lee Tae-hwan as Seo Do-yoon➡21
6. Park Won-sang as Han Cheol-ho➡46
7. Cha Kwang-soo [ko] as Son Hyun-seok
People around Oh Yeon-joo
8. Kim Eui-sung as Oh Seong-moo➡51
9. Lee Si-eon as Park Soo-bong[9]➡34
10. Nam Gi-ae [ko] as Gil Soo-sun
11. Heo Jung-do [ko] as Park Min-soo
12. Kang Ki-young as Kang Suk-beom[8]➡33
13. Lee Se-rang [ko] as Gil Soo-young
14. Ryu Hye-rin [ko] as Sun-mi
15. Yang Hye-ji [ko] as Yoon-hee
Others
16. Kim Ik-tae [ko] as medical staff
17. Noh Haeng-ha [ko] as Kim Yoo-ri
18. Ri Min [ko] as Team Leader Park
19. Seo Gwang-jae [ko]
20. Yang Seung-geol [ko]
21. Seol Ji-yoon [ko]
22. Park Geon-ryool
23. Lee Yoon-sang
24. Yeo Woon-bok
25. Kang Chan-yang
26. Park Sung-taek [ko]
27. Dong Yoon-seok
28. Hwang Yoon-geol [ko]
29. Kim Kwang-hyun [ko]
30. Min Joon-ho
31. Yoo Pil-ran
32. Park Seon-woong [ko]
33. Jang Moon-seok [ko]
34. Cheon Ye-won [ko]
35. Park Geon-rak [ko]
36.Jo Sung-hee [ko]
37. Joo Dong-hee
Special appearances
38. Park Choong-seon [ko] as Kang Yoon
39. Kim Na-woon as Yoon Mi-ho➡46
40. Seo Shin-ae as Kang Soo-yeon➡18
41. Choi Min-young as Kang Joon-seok
42. Hwang Seok-jeong as Webtoon Writer (episode 6)➡45
43. Ahn Se-ha as Kim Poong-ho➡30
44. Kim Jung-geun [ko] as Anchorman (episodes 1, 4)
45. Heo Il-hoo
