Guild thief

The guild thief was of course a thief who was a ranking member of a city's thieves' guild, as opposed to those lone conmen and cat burglars who operated solo or perhaps with a few others.

Society
The result of their membership in the thieves' guild was that they had access to assets and training that other thieves lacked, making a guild thief considerably more dangerous and resourceful to those their guild might target.

Those who chose to become a guild thief could from many walks of life, though typically rogues were the most likely to choose to join the thieves' guild of their chosen city. Depending on the attitude of the city, however, even arcane spellcasters might choose to join in order to further their own studies.

Abilities
In a fight, a guild could deliver sneak attacks of increasing deadliness and evade surprise attacks and flanking attacks with uncanny skill.

A guild thief was good at using doublespeak to talk their way into a good deal or out of trouble.

A guild thief could gain the ability to command lower-ranking members of the guild. The higher their reputation, the more assets and minions they could call upon.