The Crusader Bridenbrad quest-chain in World of Warcraft: Wrath of the Lich King. I didn't "cry", but my throat choked up...
"Bridenbrad is named for Bradford C. Bridenbecker, the brother of Robert Bridenbecker, Blizzard's Vice President of Online Technologies. He was the city manager of La Habra, California, not far from Blizzard's offices in Irvine, from 2002 until his death from cancer in 2007. He was also an avid player of World of Warcraft. In the Wrath of the Lich King manual, he is listed under "Special Thanks" as "Bradford C. Bridenbecker R.I.P. 6.18.2007".
Robert Bridenbecker revealed in the World of Warcraft 5th anniversary interviews that shortly after his brother's death, he sent an e-mail to Blizzard to request a character be created in his honor. Chris Metzen, who had attended Brad Bridenbecker's funeral, heard of this and offered one of two ways: To add him as part of the main storyline for World of Warcraft: Wrath of the Lich King, or to give him his own epic quest chain. Under the direction of Metzen and Alex Afrasiabi, the Bridenbrad quest chain was created in tribute to Brad Bridenbecker's"
It's a tragic quest; Crusader Bridenbecker, a valiant Paladin of the Argent Crusade, has gone missing. Tirion Fordring, the leader of the Crusade, tasks you to find this hero and bring him home. Upon finding the missing paladin, he confesses that in his battle against the Scourge (undead) he contracted the Undead Plague, for which there is no cure.
Tirion, upon hearing this, tasks you to seek out the Great Powers of the world; Keeper Remulos, leader of the Druid Enclave, Alexstraza the Life-Binder, Queen of the Red Flight of Dragons; and even Adal, who is basically Light Incarnate (think a race of crystal angels). All of their methods fail, and Bridenbrad thanks you for your efforts before resigning himself to his fate. But as he dies, Adal and two other Naaru appear from overhead, and raise the fallen Crusader to the heavens, promising that he shall know "Eternal Paradise". It's a LOOOOOOOONG quest-chain.... but completely worth it. Without a doubt, one of the most emotionally tugging questchains in the game, right up there next to the Darrowshire chain.
http://www.youtube.com/watch?v=1dTxcHulFBI