This Category is Corrupted
Any of the Old Gods could qualify for this category, so I'll just ask for the one who is responsible for corrupting Deathwing.
Who is N'zoth?
Starfall
Balance Druid
An iconic raid boss from Classic was finally reborn in mount-form when this mount was added in Wrath of the Lich King. I guess it was probably one of the 'many whelps?'
What is the Onyxian Drake?
This half-elf is going to become a major player in the upcoming Midnight Expansion, but Paladins might already know him from their Order Hall. What exactly did he do that was so bad, though?
Who is Arator the Redeemer?
Blizzard often likes to pat themselves on the back. The prompt text "Stay awhile and listen" that appears numerous times is actually a reference to a line spoken by this iconic Diablo character.
Who is Deckard Cain?
Fool me once, shame on you. Fool Grommash into drinking this substance twice, uhhhhhhh...
What is the Blood of Mannoroth?
Pillar of Frost
Frost Death Knight
You better be ready to be a parent to earn this mount! Befriending the Gorlocs of Sholazar Basin allows you to get an egg that can hatch into this colorful mount.
What is the Green Proto-Drake?
The Elemental Lords of Azeroth are constantly fighting either each other, the titans, or the players. We fight two of them as raidbosses, but these two other siblings have been much nicer towards mortals.
Who are Neptulon the Tidehunter and Therazane the Stonemother?
You could find Azeroth appearing on your TV back in 2007 in a commercial. In it, someone gets on this truck instead of a normal mount, proclaiming it to be "4 wheels of fury."
What is the Toyota (Tacoma)?
What is the Corrupted Ashbringer?
Rampage
Fury Warrior
This MoP faction stationed in the Jade Forest should be known to any aspiring mount collectors, as they provide multiple mounts. You even get to help raise them!
What is the Order of the Cloud Serpent?
DAILY DOUBLE
Prophet Velen hasn't always had a great relationship with his brothers. After they took a dark bargain with Sargeras, these two Eredar each were given not-so-flattering titles from the remaining Draenei.Who are Kil'jaden the Deciever and Archimonde the Defiler?
Maximillian of Northshire, an iconic questgiver from Un'Goro Crater, is a clear homage to this character of classic literature, given his mistaking things for dragons and the toy windmill you get from his quests.
Who is Don Quixote?
This Warden accompanies Khadgar throughout WoD before she, you guessed it, got corrupted and helped the Legion steal Illidan's body from the Vault of the Wardens.
Who is Cordana Felsong?
Light of Dawn
Holy Paladin
You had better be ready to go on a scavenger hunt all around Uldum! Clicking on a hidden figurine located somewhere in the zone lets you obtain a title and this mount. And yes, I need the full name.
What is the Grey Riding Camel?
Legion players fondly remember this questing NPC whose story ended on a tragic note. Despite his mana-addiction, he remained an ally until the very end.
Who is Runas the Shamed?
A quest chain in Hillsbrad Foothills started by Brazie the Botanist that is a homage to this game. It the quests themselves weren't on the nose enough, the reward for it all is a singing sunflower.
What is Plants vs Zombies?
Ok Medivh got corrupted by Sargeras, but really it was his mom's fault. This former guardian got corrupted by the Avatar of Sargeras and passed it on to baby M.
Who is Aegwynn?
Strike of the Windlord
Windwalker Monk
This mount was originally given to brave souls who completed the Glory of the Raider Achievement on 10-man in WotLK Naxx. It was retired after just one patch, but you can still bid on it using the Black Market Auction House.
What is the Plagued Proto-Drake?
We still don't know where this scheming primal incarnate went after the events of Dragonflight. But that didn't stop players from remembering his full name and title, right?
Who is Iridikron the Stonescaled?
A Rogue Legion Legendary called the "Zoldyck Family Training Shackles" is a clear reference to this iconic shonen anime's assassin family.
What is Hunter x Hunter?