Song Jieun and Bang Yongguk i freaking love their collab in Going Crazy which was released in 2011. look at my man trying so hard to be in character (as an obsessed stalker) for those who didnt know, Jieun filed a lawsuit last year and left their company (im happy for her tho. she need to get away from that company, but im sad because i know this collab wont happen again in the near future)
Younique Unit - since Luhan and Henry both left the company. They'll probably focus on their NCT performance units if they need to do something like this again, but I really liked the cross-group blend.
We all know this wonderful collab won't happen again... (With Jjong resting in peace, Sulli's departure, and almost non-existing f(x))
confession: this was actually the song that got me into kpop; gee got me into SNSD + found my bias Yoona amazing collabs in the past that won't happen again: SNSD x 2pm SNSD x Wonder Girls SNSD x Kara SNSD x Big Bang SNSD x Jessica = OT9
Oh my god fetus Yongguk. This will probably never happen(it's not impossible, just unlikely) So many disbanded groups, and now Jonghyun, this could obviously never happen again.