I've had a trinket missing for this one for quite some time. I finally got an offspec one from Sapphiron though.
[Temple of Ahn'Qiraj]
Having played WoW since May 2006, C'Thun is something major for me. I never got to see him as I only did a few ZG/MC raids before Burning Crusade hit. That's why it feels like a huge thing to be able to go back and one-shot him in a PUG like I did today.