Azog was a great Orc of Moria, the leader of the Orcs who held the old Dwarf-realm in the later Third Age.1
In 2790 Thrór, the exiled King under the Mountain, went to the East-gate of Moria to look on the halls of his fathers. Azog killed him and branded the name Azog on his severed head; when Thrór's companion Nár stooped to take it, Azog bade him drop it and be gone, and threw him a bag of coins as his fee.1,2
The Dwarves answered with the War of the Dwarves and Orcs. For years they hunted the Orcs through the Misty Mountains, and in 2799 they came at last to the Dimrill Dale before the East-gate for the Battle of Azanulbizar. Late in the day Náin, Dáin's father, called Azog out of the gate and was killed by him; Dáin Ironfoot, then only thirty-two, overtook Azog and cut off his head, which the Dwarves set on a stake. The Dwarves won, but at such a cost that they would not enter Moria, for Dáin saw that Durin's Bane still waited inside.1,2
His son Bolg led the goblin host at the Battle of Five Armies some hundred and forty years later.1
On screen
Where the best-known adaptation departs from the books. Nothing in this section is evidence for the books themselves.
In Peter Jackson's Hobbit films Azog survives Azanulbizar, losing an arm, and hunts Thorin's company across Wilderland; he and Thorin kill each other on Ravenhill. "The Defiler" is the films' title for him. In the books he dies at Azanulbizar, slain by Dáin.3,1
Sources
Citations name the chapter rather than the page, so they work in any edition. The colour of each note shows what kind of source it is.
- Appendices Tolkien's own appendices to The Lord of the Rings.
- Adaptation Films and other adaptations. Never evidence for the books.
- Appendices The Lord of the Rings, Appendix A, III, “Durin's Folk”
- Appendices The Lord of the Rings, Appendix B, “The Third Age”
- Adaptation Peter Jackson's film trilogy (2001–2003), The Hobbit trilogy (2012–2014)