Yup, mine is the alltime gateway for many people, Boys Over Flowers!!!! <3<3<3
The first drama I watched was Boys Over Flowers but the one that made me enter this land with no return ticket was City Hunter , my second kdrama! :P
One day this channel was passing an episode of Boys Over Flowers and I looked it up on the net, and on the recommendations I saw Heartstring and that weekend I binged watch the two of them. So I don't know witch one of the 2 really hooked me up, loved them both equally.
Mine was Hana Yori Dango, and when I heard there was a Korean remake I had to watch it :D
I think It's My Girl :)
"A Love to Kill" was definitely my first kdrama but didn't start my kdrama addiction since i watched mostly Japanese dramas (+ was into jpop) back then. now it's been a long time since i last saw a drama from Japan, and I'm only into Korean dramas & music now *-* I think "You're Beautiful" might have been the first of the Korean era ^-^
First kdrama I started watching was God's Gift - 14 Days. Loved it, but after six episodes I learned that City Hunter would only be on Netflix for another few days, so I switched to watching that. So City Hunter was the first I finished.
Sad Love Story... Watched it in 2011 and it's still my favorite drama ^^
mine was probably autumn in my heart ;_;
My first k-drama, was Faith (2012) starring Lee Min Ho <3 i fell in love with k-dramas ever since.
My best friend introduced me to Flower Boy Ramen Shop in 6th grade. But it was not until I watched I Hear You Voice freshman year that I began earnestly watching them.  (I watched IHYV in debate camp, the one thing I enjoyed there!)
City Hunter was my gateway drug khm I mean drama :)
my first kdrama was dream high, because i saw a gif from it and thought it was pretty. after that i started watching more and more but the first drama i LOVED was master's sun.
FAITH was my gateway Kdrama. (I did watch a Taiwanese drama before it called Autumn's Concerto)