As anyone who's seen heist films knows, the gathering together of a crew (or "string" as Donald E Westlake's Dortmunder novels call it) really sets the tone for the rest of the caper itself. Each member of a string has a specialty that makes them essential to the task at hand, from safecracking to infiltration to crowd control. The television show (and subsequent roleplaying game) Leverage divided these specialties into the broad categories of Hitter, Hacker, Grifter and Thief. For my Heist D&D game, these roles are going to be covered by the four standard classes from Basic D&D.
These Dungeon String posts are my ideas on how each D&D class can fit into the heist milieu. Though the Thief class seems like it would cover the traditional pickpocketing, lockpicking and stealthy elements of a caper, this is a fantasy heist. There are going to be vault doors closed by magic, exploding rune traps, gelatinous cubes making security sweeps in the sewers below, plenty of room for a wide variety of unscrupulous characters. But since they are the backbone of any good heist, let's start with the Thief.
In a game where disarming traps and dodging security are commonplace occurrences, the Thief is the obvious utility player, acting as dedicated burglars, ranged combat specialists or expert lookouts. On top of their obvious Thief skills and alertness bonuses, Thieves also have the Backstab ability, which not only covers striking from the shadows with a knife to the back, but also ranged attacks from long distances. A Thief armed with a repeating crossbow in a high vantage point could hold off advancing enemies until the job is done or the plan has to be abandoned.
As many people have already noted, the standard B/X Thief is kind of a chump, with low hit points, okay saves and an alright attack progression. But on top of that, the Thief isn't any good at his job. I know that the Player Skill vs. Character Skill debate has been hemmed and hawed over by the OSR blogging community as a whole, specifically having to do with Thief skills, but it still stands that a standard Thief is much, MUCH worse at being a Thief at 1st level than a Fighter is at being a Fighter and so on. A starting Fighter with decent stats has about a 25-40% chance of being able to hit most monsters. A Cleric has a 33-50% chance of turning undead of around his level. But a starting Thief is more likely to succeed at his saving throw against a poison trap than his actual Trap Removal roll.
No more. In the Heist D&D campaign, I'm planning on using a modification of Beyond the Black Gate's Swords and Wizardry Thief class with the unified Thievery skill starting out at a 35% success rate. I figure that a modification like this puts the Thief on more even ground with the rest of the Basic classes and as a result, it will hopefully encourage more stealthy maneuvering and thiefly behavior.
Picture from Claudio Pozas' art gallery on ENWorld