Overlord Mor'ghor is the leader of the Dragonmaw Clan on Netherwing Ledge in Shadowmoon Valley and oversees all operations that take place there. It is presumed that he is Zuluhead the Whacked’s second in command and is therefore the current Chieftain of the Dragonmaw when the player encounters him.
From his meeting with Lady Sinestra, we can assume that he was an orc of high standing during the Dragonmaw's stay at Grim Batol and also an agent of the black dragonflight during this time. It is possible that he supplied Deathwing with information on Alexstrasza and the Dragon Soul's whereabouts which eventually led to the events that took place in Day of the Dragon. However, if this is the case, it means that Mor'ghor was either not present at the The Battle of Grim Batol, having already traveled to Outland with his chieftain or he has only recently arrived there, which would mean that he survived the Dragon Queen's wrath and possibly served under Nek'rosh Skullcrusher. The latter theory is probably the more likely of the two, given Nek'rosh's connection with the Black Dragonflight. (See Dark Horde)
Whatever the case, it is known that Mor'ghor now serves under Zuluhead and Illidan Stormrage as a Fel Orc and aids the Illidari in collecting valuable resources from the Netherwing Ledge, much to the dismay of the Netherwing. However, Mor'ghor still secretly serves the Black Dragonflight as is apparent from both his conversation with Lady Sinestra and the player's conversation with the Murkblood overseer in the Netherwing Mines. From both of these events, we know that although the Dragonmaw under Mor'ghor have been using much of the resources that they take from the Ledge to supply Illidan's armies- They have also been taking much of it for themselves and either selling it or giving it to the Black Dragonflight in return for mounts and the favour of the Dragonflight's master
Cataclysm
Mor'ghor, having fled from Outland, now resides in Dragonmaw Port, where he has become the new Warchief of the Dragonmaw Clan. He is unwilling to aid the Horde in the Twilight Highlands, which - in combination with his bloodthirsty nature - leads to a rebellion led by battlemaiden Zaela which ultimately results in his death.