Some sort of Archer/Mage/Illusionist mixture. Mainly stealth oriented.
Primarily an Archer in Light Armour, dealing physical damage from long range, my Bow enchantments dealing extra magical/poison damage. Running and sneaking around, pick locks and pockets, that sorta Thief stuff.
The Mage and Illusionist aspects are secondary. On the Mage end of things, I would have a few deadly and highly potent short-range spells to quickly wipe out weakened targets that get too close. On the Illusionist side, I have the odd Charm spell to make enemies fight for me, but mostly the Illusionist aspect is so I can cast an array of Invisibility spells and get out if everything goes horribly wrong.
I've actually built a character that embodies this perfectly in Oblivion, actually. My Major skills are Marksman, Light Armour, Sneak, Illusion, Mercantile, Athletics, and Alchemy. My primary spells are Invisibility, a slow regeneration spell, Night-Eye, and a spell that deals massive damage to whoever I touch with it. My Bow is enchanted for extra damage, and my Alchemy lets me further add poison onto my attacks. So I sneak attack for extra backstab damage, then go Invisible and Sneak some more until the poison has run its course. I love my Archer. >:)
It's a pity there's practically no other RPG series that gives me the freedom to create an Archer that plays the same way.