Heroic Sha of Fear - If you defeat the Sha of Fear in Terrace of Endless Spring on Heroic difficulty, you are granted the title: The Fearless.
Heroic: Will of the Emperor - By defeating the Will of the Emperor in Mogu'shan Vaults on Heroic difficulty you are rewarded the title: Delver of the Vaults.
Now, you may well remember Glory of the Cataclysm Raider and Glory of the Cataclysm Hero.
Both reward a mount. The first one being from raids, thus defeating certain bosses and completing achievements on both normal and heroic difficulty and the second one from heroic dungeons.
In Mists of Pandaria, there are similar achievements that reward mounts:
Glory of the Pandaria Hero: Reward: Reins of the Crimson Cloud Serpent
Glory of the Pandaria Raider: Reward: Reins of the Heavenly Crimson Cloud Serpent.
These new mounts are now account-wide. All mounts are shared between all the characters nonetheless.
At this time, there are no mounts on the heroic loot table of bosses, such as the Pure-blood Firehawk from Heroic Ragnaros or Life-binder's Maiden from Heroic Dragon Soul.