Scarlet Mail Set

The Scarlet mail set which still drops in the Scarlet Monastery instances were iconic for someone who leveled a Hunter or Shaman before Heirlooms. Even though the items had Strength, many people took these as upgrades from their leather to mail gear as they hit level 40.

Hunter

Chain of the Scarlet Crusade
Blood Knight War Helm
Splintermark

Shaman

Chain of the Scarlet Crusade
Fel Iron Hatchet
Raging Berserker's Helm

Cataclysm Combos - Tier 2

Tier 2 gear is mostly found in Blackwing Lair with the exception of the legs, which drop from Ragnaros in Molten Core. The head used to drop from Onyxia, however as she is now a level 80 boss, it now drops from the level 60 Nefarian.

Druid - Stromrage Raiment

Hunter - Dragonstalker Armor

Mage - Netherwind Regalia

Paladin - Judgement Armor

Priest - Vestmemts of Transcendence

Shaman - The Ten Storms

Warlock - Nemesis Raiment

Warrior - Battlegear of Wrath

Level 60 Epic Pvp Gear - Rogue

Transmogrify yourself to an Old School Rogue and hang around in Blackrock Mountain, bring back some old memories, and nightmares.

Field Marshal's Vestments - Alliance
Warlords Vestments - Horde

Level 60 Epic Pvp Gear - Warrior

Low level pvp gear is easy to come across these days, making it a not so horrifc grind to get some good Transmogrify gear. The level 60 parts are sold for as little as 125 honour, and some only being 70.

Field Marshal's Battlegear - Alliance
Warlord's Battlegear - Horde

Cataclysm Combos - Tier 1

When Cataclysm came, new class and race combos were introduced. In 'Cataclysm Combos' I will be showing these new combos and how they look in previous tier gear, starting with Tier 1.
Tier 1 gear comes from various Molten Core bosses and trash drops.

Druid - Cenerion Raiment 

Hunter - Giantstalker Armor

 Mage - Arcanist Regalia

Paladin - Lawbringer Armor

Priest - Vestments of Prophecy

Shaman - The Earthfury

Warlock - Felheart Raiment

 Warrior - Battlegear of Might

Holy Cow

 

Tauren Priests are a fun one to search for gear that will look good to Transmogrify, there is also nothing better than a Tauren in a hat.

Heroes' Shoulderpads of Faith

Furious Gladiator's Mooncloth Robe
Whitemane's Chapeau
Voidweave Cilice
Inferno Gloves
Ancient Scepter of Sue-Min

Dungeoneering Guide

Night Elf Mage

Night Elf Mages were another race/class combo that became playable in Cata, although I don't see many around. I was trying to get a Highborne look, with bright, glowy, arcane like colours.

Hallowed Garments
Mantle of the Tempest
Crown of Endless Knowledge
Belt of the Depths
Arcanist Gloves
Xintor's Expeditionary Boots
Saronite Spellblade
Prison Manifest

Another Dark Ranger

Another Dark Ranger look for transmogrification, but this time it's mail.

Avenger's Armor
Rip-Flayer Leggings
Renegade Boots
Blackforge Girdle
Blackforge Gauntlets
Striker's Mark
Cloak of the Black Void
Blackforge Cowl
Stylish Black Shirt

Sentinel

Sentinel's armour is a tricky one to find. The shoulders are mail, and so I have found some other mail gear that gives the same colour and a simular look to the Sentinels that we find in game.

Impenetrable Pauldrons
Abyssal Mail Greaves
Scaled Greaves of Patience
Impenetrable Breastplate
Fathomheart Gauntlets
Frostreaver Crown
Netherfury Belt

Jedi and Sith

Now you can use Transmogification to become a Jedi Master or a Sith Lord!
Remember the first time someone in your guild linked 'that sword that looks like a lightsaber' well now finally you can use it. These outfits are all cloth, so with the sword (ahem, i mean lightsaber) they are perfect for a mage and a warlock. The Wowhead Model viewer does not show the swords correctly, but trust me, they look brilliant.

Jedi

Spellfire Longsword
Living Cowl
Durable Robe
Phasing Boots
Bright Belt
Zaetar's Gloves
Resilient Mantle

Sith

Teebu's Blazing Longsword
Nightsky Cowl
Batwing Mantle
Black Velvet Robe
Ghostweave Belt
Kayser's Boots of Precision
Black Mageweave Gloves

Bluffwatcher

Get out of Orgrimmar, go to Thunderbluff and be one of the guards instead! The Bluffwatchers wear all leather, and I found a two handed axe that looks similar to the one which they wield. Bluffwatchers do not wear any gloves or wrists so something that matches the red of their armor may be a good idea.

Feral Harness

Feral Leggings

Feral Shoes

Ranger Shoulders

Bard's Belt

Boahn's Fang

Cracking Skulls

Ey mon! Dis troll be crackin' da skulls. You can't own a Troll without transmogging it back to their voodoo glory. If you are unable to get the recent gear in Zul'Aman, it is possible to obtain the old Burning Crusade badge gear which have very similar styles.

High Chief's Crown
Pauldrons of Gruesome Fate
Plate of the Shaman King
Bloodthirster Wargreaves
Giant - Sized Gauntlets
Bladed Steelboots
Exalted Girdle
Hate Forged Cleaver

Light's Justice

Pally's have some great coloured sets, it's a shame the glow from the head could not be captured on the wowhead model viewer. Everyone who plays a Paladin must know that the brighter the Pally, the better the Pally (that may be a fact I just made up.)

Light's Justice
Triptych Shield of the Ancients
Crown of Empowered Fate
Girdle of Lordaeron's Fallen
Uther's Ceremonial Warboots
Sunblessed Breastplate
Truth Bearer Shoulderguards
Felsteel Leggings
Felsteel Gloves

Booty Bay Bruiser

A fairly simple character to make if you have a leather working. The boots and gloves from the original BB Bruisers are leather, so would not be able to be transmoggged with the mail parts of the set so I have had to make do with some others. Also added shoulders, as you can't play a character with no shoulders, how will they protect themselves!

Heavy Scorpid Vest
Heavy Scorpid Leggings
Heavy Scorpid Belt
Nerubian Boots
Nerubian Gloves
Battle Star

Red Nemesis

This is a red version of the Nemesis lock set, and because it has no class restrictions can be transmogged by priests and mages too! These items all drop from The Burning Crusade instances, except the staff, which is a Blackwing Lair drop.

Vermillion Robes of the Dominant
Mantle of Three Terrors
Demonfang Ritual Helm
Gloves of the Deadwatcher
Sash of Serpentra
Staff of the Shadow Flame

Almost Tree Form

I love the shoulders for this one, I may hunt around and look for some more matching leafy gear to make the character look like a big tree like mess!

Serpentcrest Life-Staff
Living Breastplate
Thoriumweave Cloak
Forestwalker Kilt
Grips of Lunar Eclipse
Might of the Timbermaw
Mantle of Autumn
Bright Yellow Shirt

Diggy Diggy Hole

This creation was inspired by The Yogscast, and anyone who is a fan will understand. If you don't understand but you do own an enhancment shaman with axes which happens to be a dwarf, this needs to be done!

Shovelphlange's Mining Axe
Cragfists
Foreman's Reinforced Helmet
Heavy Scorpid Vest
Heavy Scorpid Legs
Heavy Scorpid Shoulders
Yellow Lumberjack Shirt
Flamescale Boots

A Soothfancy Gnome

 I came across a little gnome in Tanaris that looked like this, and I instantly felt the need to recreate it and share it with the people of the Internet, so they too can create gnomes that look like this. They can run around their servers or battlegrounds being a stylish little genie gnome.

Red Mageweave Shoulders
Robes of the Royal Crown
Runecloth Gloves
Dawnspire Cord
Spellweaver's Turban

Orgrimmar Guard

Most people know this outfit, however if you didn't here it is! As it is all leather, to be able to use this in battle you would need to be a rogue, or a Hellscream obsessed druid. Unfortunalty all the gear for this are random world green drops, so good luck!

Sentinel Girdle
Sentinel Boots
Sentinel Gloves
Sentinel Trousers
Sentinel Breastplate
Cabalist Spaulders
Mistyreed Torch
Grunt Axe

Uh Batman?

Okay, so this is pretty silly, but I was just playing around and couldn't resist after finding the head.

Mask of Inner Fire
Black Dragonscale Leggings
Black Dragonscale Breastplate
Gray Woolen Shirt
Swiftarrow Belt
Gloves of Taut Grip
Boots of Unsettled Prey
Spored Tendrils Spaulders
Shrapnel Star

Tirion Fordring

Transmogging into the famous Paladin is very easy (aslong as you are a paladin that is) Tirion basically wears tier 6 chest, legs, and shoulders, with the belt and boots being boss drops.

Pearl Inlaid Boots
Girdle of Hope
Lightbringer
Argent Crusader's Tabard