Yoo Dong Geun (Drama's What Happens to my Family, The Most Beautiful Goodbye, Marry Me Now. He was also in Gu Family Book, East of Eden, Only You, and many others). When I first watched him in What Happens to my Family I was crying so hard during some of his scenes! I think he is an amazing actor!
Jeon Kuk Hwan. Seen him a ton of stuff over the years, he's best at playing villains / bad fathers, like he did in Bad Guy and Doctor Stranger and currently he's playing Hyun Bin's father in Crash Landing.