I'm sure someone else has already recommended this movie but god damn, the original 2003 OldBoy is a fucking classic. Might actually be one of the best drama action films I've ever seen. The acting, the writing, the cinematography, all of it so perfect. Easily one of the most interesting action movies I've ever had the pleasure of enjoying as well. Extremely in-depth character development that leaves you wanting more and more. Highly recommend it for anyone wanting to get into Korean action movies or even Korean drama movies.