Thief - SHADOW / 1 Bar Bandit [ The Black Sky Guild NA ] - ESO

SHADOW
One bar thief build focused on invisibility and avoiding combat. It's fast, has a lot of maneuverability in tight areas and makes escaping conflicts easy. Using Blade of Woe on an NPC will instantly proc invisibility from Sithis' Touch. This overlaps perfectly with the Shadowstrike CP ability giving you around 6 seconds of free invisibility after a BoW kill. You can nullify aggro using Immovability/Invisibilty potions. These can be a little tricky to master. Use them when picking the pockets of dense crowds or when you just don't want to be seen.

Race
Khajiit are designed for thieving. Wood Elves have a nice speed bonus.
Khajiit (Cutpurse, Feline Ambush)
Wood Elf (Hunter's Eye)

Attributes
All into either Magicka or Stamina.

Gear
You could swap out Ring of the Wild Hunt for Snow Treaders (Antiquities). Slimecraw could be replaced with Chokethorn for more Magicka recovery or another helm which increases Magicka. Equip what suits you.
5 X Vesture of Darloc Brae (Northern Elsweyr Overland)
5 X Sithis' Touch (Gold Coast Overland)
1 X Helmet of Slimecraw (Wayrest Sewers)
1 X Ring of the Wild Hunt (Antiquities)
All Medium Armor, Magicka Enchants, Infused or Divines trait. 
Sword and Shield on the front bar, Dual Wield / Staff / 2-Handed on the back.
Jewelry has Infused trait with glyphs of Potion Speed.

Skills
Main Bar - thief
Slot 1: Killer's Blade (NB) - Flex slot.
Slot 2: Hypnosis (Vamp) - 5 second 360 degree stun that cannot be blocked. When a guard comes at you, stay still, pop this, then run.
Slot 3: Race Against Time (Psijic) - Increases movement speed by 30% and grants immunity to snares and immobilizations for 2 seconds. Pop this while fleeing, after Hypnosis, or if you want to get somewhere fast. The beauty of this ability is that you won't break stealth when casting.
Slot 4: Shadow Cloak (NB) - Become invisible for 3 seconds. Hit this after Race Against Time.
Slot 5: Concealed Weapon (NB) - While slotted, your Movement Speed while Sneaking or Invisible is increased.
Ultimate: Bolstering Darkness (NB) - Slot what you want here.

Back Bar - DPS
You can run whatever DPS setup you want on the back bar. You need to burn down NPC mobs fast if needed so slot accordingly. I also run Concealed weapon on the back bar.

Passives
Legerdemain: Trafficker, Light Fingers, Locksmith, Kickback.
Medium Armor: Improved Sneak.
Vampire: Dark Stalker, Unnatural Movement.
Thieves Guild: Finders Keepers, Swiftly Forgotten, Haggling, Clemency, Veil of Shadows.
Dark Brotherhood: Blade of Woe, Scales of Pitiless Justice, Padomaic Sprint, Spectral Assassin.
One Hand and Shield: Battlefield Mobility. Bracing doesn't break stealth so you can use this to accurately maneuver in tight corners or large crowds.

Champion Points
First thing you want to unlock is Cutpurse's Art but you have to spend a few points to get it, 160 to be exact. After that the rest is optional as to what order you unlock abilities. If you're not running the Ring of the Wild Hunt, you'll need Steed's Blessing, swap out Homemaker or Infamous.

Buff Food
Wirchmother's Potent Brew. Buffs Health, Magicka and Magicka recovery.

Potions
ALWAYS slot Potions of Immovability/Invisibility in your quickslot. They're a good last resort, handy if a pick pocket goes sour or you're trapped indoors with a guard. Eat them like candy. They'll last a lot longer coupled with Potion Speed enchants (Oru) and Infused traits on your jewelry.
Immov / Invis: Water + Blue Entoloma + Columbine + Namira's Rot
Immovability: Water + Columbine + Namira's Rot
Invisibility: Water + Blue Entoloma + Namira's Rot
There are of course other herb combos but I like the health boost from this particular recipe.

Mundus Stone
Take your pick based on what seems weak.
The Steed (Increases Health and Movement Speed)
The Atronach (Increases Magicka Recovery)
The Mage (Increases Max Magicka)