What was your first Korean movie that you ever saw?

Mine was Oldboy. Saw it back in Canada.

301, 302. Fairly bleak movie. I wouldn't really suggest it unless you've seen and enjoyed The Cook, The Thief, His Wife and her Lover. Or you generally enjoy Peter Greenaway films.

Friend (친구).

Watched it with a friend at the Defense Language Institute back around 2003. I was studying Arabic, he was studying Korean. I remember being mildly jealous that Korean language cinema seemed much more interesting than the majority of Arabic language cinema, but to balance that out a bit I also remember thinking all the Korean music he listened to was completely terrible.

Attack the Gas Station

I didn't even know what Korea was, beyond crazy old North Korea, when I saw this. Thought it was pretty funny/good at the time (2000ish)

"Attack the Gas Station". After that I think it was "Sex is Zero".  After that, hmm..."The Classic" maybe?

Plan Man (플랜맨)

I was at a Korean cultural event and they showed this movie. A decent comedy with a touching backstory for the protagonist.

개같은 날의 오후 or A Hot Roof

https://mydramalist.com/13853-a-hot-roof

Jesus, None of my poll selections are worth shit. hahahahaha

Not a movie, but in my HS and early uni anime days, I watched an anime adaptation of a Korean drama called 'Winter Sonata'.
Was pretty cheesy, but it didn't take much to impress a young adult with mild weabooism.

My first Korean movie was M*A*S*H*. 

No, but really, my first REAL korean flick was Adjosshi. Your typical young-girl-befriends-brooding-stranger revenge story. I enjoyed the crap out of it! 

100 pound beauty hahaha!

Shiri (1999), I saw in 2002...

It was the first blockbuster post IMF crisis.

North Korean spy, South Korean agent, a beautiful woman, lots of action and intensity.

I enjoyed it.

The first Korean movie I saw at the movie theater was Spring, Summer, Fall, Winter... and Spring (2003).

It was beautiful on the big screen.

My Wife is a Gangster (2001) I saw in a video bang, the first film i technically saw while in this country.

It was hilarious!

The Host (2006)

Does “Snow Piercer” count?

"Take Care of My Cat", I think.

Does “Snow Piercer” count?

Yup! I'm seeing that tomorrow in Myeongdong and my GF got me the deluxe boxset Blu-Ray for my bday.

Love that movie. Visual masterpiece.

The Bow   I saw it back home way before I ended up in Korea.

Oldboy was the first one I saw in Korea. I think.

엽기적은 그녀   Synopsis: All tomboys are secretly super cute girly girls.

IMDB 8,1
https://www.imdb.com/title/tt0293715/

https://www.youtube.com/watch?v=AoLiQnbUqgI

Doggy Poo

The story of a doggy poo in search of meaning in his life.  Absolutely beautiful.

The VERY first one..."Please Teach Me English".

..the soon after... "Sex is Zero", "The Brotherhood of War", "Old Boy"