Skyrim Build: Thief

Thief

Intro -
The Thief is a master of stealth with loyalty to no one beyond his brothers and sisters in the Riften Thieves Guild. Walking in the shadows he swipes coin from anyone careless enough to leave it tied to their belt and makes off into the night before they realise. Utilising his skills with lockpicks, stealth, alchemy and sometimes magic this silent figure makes his riches without drawing blood. 

Race Selection -
Khajiit - This is what I personally went for, lore wise it fits and starting skills are good. Plus seeing in the dark is handy if you run a lighting mod that makes dark actually... well, dark.
Argonian - Again it works well lore wise, the starting skills are good and water breathing could add a new aspect to stealth
Wood Elf - Stealth and archery good early game stats.
Dark Elf - Alright, but not a personal choice
Other Races - Not ideal but nothing stopping them being a Thief!

Armour/Weapon Selection - 
Weapon - One handed sword - Nightingale Blade, Ebony Sword for looks. 
Off-hand - Dagger - Ebony/Daedric. Illusion spells - Calm, Fury, Fear
Armour - Light Armour - Thieves Guild, Nightingale, Guild Master.
PC ONLY -
Weapon - Fist Weapon provided by Perkus Maximus mod, Sword damage scale, called Katana.
Off-hand - Knuckles/Claw fist weapons added by Perkus Maximus. Same spells as previous.
Armour - Same as previous.

Standing Stone - 
Thief stone for 20% boost to thief stat exp gain, Lover Stone for 15% boost to all, Shadow Stone for invisibility daily power.

Skills/Perk Selection - 
Sneak - Stealth (5/5), Muffled Movement, Light Foot, Silent Roll, Silence
Pickpocket - Light Fingers (1/5), Night Thief, Extra Pockets, Cut Purse, Key Master, Misdirection, Perfect Touch, Poisoned
Speech - Haggling (1/5), Allure, Bribery, Persuasion, Merchant, Investor, Fence, Master Trader
Alchemy - Alchemist (5/5), Physician, Poisoner, Concentrated Poison, Green Thumb
Enchanting - Enchanter (5/5), Insightful Enchanter, Corpus Enchanter, Extra Effect
Illusion - Novice Illusion, Apprentice Illusion, Adept Illusion
Light Armour - Agile Defender (1/5), Custom Fit, Unhindered, Matching Set, Wind Walker, Deft Movement
One Handed - Armsman (1/5), Fighting Stance, Bladesman, Dual Flurry, Dual Savagery
Archery - Overdraw (1/5), Eagle Eye, Steady Hand (1/2)

As you can see this is a lot of perks on a lot of skills, it will in fact take you to level 59. Now I will say here that archery, illusion, enchanting and alchemy are all optional and down to personal preference, but I found my one handed and light armour alone wasn't keeping me alive when things went wrong. Which they will, often when your sneak is low. If like me you use the Perkus Maximus mod or a similar overhaul, these skills still apply, under their new names, and similar perks can be found.
Lockpicking is left out because it's a waste of perk points.

Quest Lines
Alduin/Main Story - Optional, however I advise on ignoring Whiterun early on and not letting the dragons spawn as your combat is weak till later.
Civil War - Optional.
Dark Brotherhood - Possible. For me no, but a Thief may get bored of just stealing.
Thieves Guild - Yes, in fact, this should be your first quest line, oddly enough.
Mages College - Maybe. Illusion could lead you there.
Bard's College - Maybe.
Companions - Personal Preference
Dawnguard - Yes, can join either side. 
Dragonborn - Why not?
Thane Quests - Title is useful for getting out of bounties.
Side Quests - Yes, for money.
Daedric Artifacts - Yes, thieves like trophies.

I found this build fun, but hard to play early on due to putting perks into sneak, pickpocketing and  Speech, thus leaving me with very little damage or survivability. It is fun and rewarding and a true way to play the Thieves Guild quest line, in my opinion, the best quest line. However it doesn't quite lend itself to other quest lines so well, be warned.

~Rusty