I've been discussing this with a friend and we were trying to come up with a list of actors who can really cry their hearts out. I'd love to know your choices.

Also, describe the crying scenes that really moved you.
My favorites:
Vic Zhou
in Mars - when he cried after confirming that Qi Luo was raped. he just sat there with tears dripping down his face.
in Silence - when he realized he wasn't ready to die yet and wanted to live on.
Mike He
in Why Why Love - when he pretended to be Auntie Qin's son
Gong Yoo
in Coffee Prince - when he found out that Eun Chan was actually a girl and when he said goodbye to Eun Chan, after hanging up the phone.
Hyun Bin
in Millionaire's First Love - during the wedding scene in the play (he does that crying with a straight face thing very well)
EDIT: Okay, okay, a ton of you said
Kwon Sang Woo in Stairway to Heaven (and almost every other series/movie he's been in). So I started watching Stairway to Heaven, and yes, the guy definitely deserves to be on this list. He's an expert. He can do the single tear dripping down his cheek, or the tears flowing down his cheeks silently, and even the full-blown sobbing while in fetal position. And yet, it doesn't take anything away from his masculinity. He's still as hot as ever when he cries, maybe even a little bit more attractive. Now how exactly does he do that????
EDIT: I agree with everyone who said
Ikuta Toma. Heart-wrenching indeed. You just want to reach out and hug him so badly.
(yet another) EDIT:
Yamapi (Yamashita Tomohisa) in Proposal Daisakusen and Kurosagi. All I can say is, I'm in love.