I'm obsessed with Jung Hyun-Soo from Suspicious Partner, but Ji Eun-Hyuk (lawyer friend) was also really cool. Jong Hyun Soo was such an intriguing, dark character.
Second Grim Reaper from Goblin. Awesome writing for a secondary character.
Adjumma from Healer! Simply loved her character. Was funny, independent and super smart. Very loyal even though she pretended to not care. More characters like her, please!
Kim Byung-Yeon from Love in the Moonlight (the guard/best friend). My god, he was perfect in every way. Strong, mysterious, caught in his own situation, but still as loyal as possible.
I loved Wendy from Falling for Innocence. Great comic relief.
Yoon Myeong-Joo from Descendants of the Sun was one of the best female characters ever. Loved her character. She was strong, level headed, brave, had great work ethic and knew what she wanted. Never meek or whiny. What an amazing role model.