So you want to play a Thief in 1st Edition? Let’s talk about what to expect, how to use it, and how to make it your own (besides personality, of course).
Like Fighters, Thieves are available to every race but with unlimited level to all but half-orcs (who top out at 8 with 18 Dexterity and 6 with less than 17). Not only that, but thieves have great multi-classing options with all of the non-human races, meaning that it is worth considering multi-classing as a thief with any character that is able if for no other reason than to have that unlimited growth potential after other level maximums have been reached. If nothing else, you can push Thief to level 10 and be able to establish a gang of thieves for late game play whereas strongholds of other classes are generally denied to non-human characters.
To be a Thief, the character must have at least 9 Dexterity, but 15 Dexterity or more buys you a 10% XP bonus. A Dexterity of 13 is the minimum to have no penalties to your thief capabilities (though penalties at 11 and 12 are minimal) and bonuses to thief abilities start at 16, as do reaction adjustments vital to helping your thief be the surpriser and not the surprisee as he does his intelligence gathering work out ahead of the party.
Like anyone, the thief benefits from extremely high Dexterity with better armor class above 14 and from very high Constitution (above 14) with bonus HP. The PHB says “high intelligence is also desirable,” but I can’t for the life of me figure out what for other than the benefits that accrue to any class with high intelligence: knowing more languages and succeeding on more intelligence checks. If anything, it seems less important to a thief since at 4th level they start being able to read languages without having a language slot available some of the time. If you find anything to explain it, let me know.
While thieves aren’t slouches in combat (especially with backstab), the thief’s role is scouting, intelligence, and removing obstacles to the party. To help in these responsibilities, they have increasing chances with level to pick pockets, open locks, find and remove traps, move silently, hide in shadows, hear noise, and climb walls. At low levels, their chance of success in these tasks is generally low, but better than the 0% chance non-thieves have in the same task.
If you like solo missions and vital tactical decisions, the thief has the skills to and the role to let you do that, leading the way and taking out traps and sentries alike to make things easier for the party.
Thieves also get a chance to read languages starting at level 4 and, starting at 10th level, can start using magic scrolls, but they have a chance of failure as if they were 5 levels too low to cast the spell, not bad!
If you’re coming from later editions of Dungeons and Dragons, you may be surprised at how standardized the Thief is in 1st edition. On the one hand, this enhances the focus on character personality as a differentiating characteristic. On the other hand, you probably want something mechanical. Let’s see what we can come up with.
First of all, having all of the race options be so viable is a big help to having a variety of options. We’ve mentioned that each of these races have multiclass options that can set your character apart in the extreme, but all of the thief functions also have racial adjustments. Extreme cases include +15% to find/remove traps for dwarves, +15% to hide in shadows for halflings, and -15% to climb walls for gnomes and halflings. There are also many 10% shifts sprinkled among the races, too many to mention. A 10% or 15% difference may seem small, but at low levels this can mean doubling or nearly doubling your chances for many of these functions (a dwarf goes from 20% to 35% to remove a trap) and at high levels it can mean halving or negating a chance of failure (at level 11 a normal thief has a 30% chance to fail disarming a trap while a dwarf has only a 15% chance, at level 14 this is 15% and 0% respectively).
As a forward scout and a cagey fighter, you have a lot of opportunity to differentiate your thief through behavior. How reckless or cautious is he? Does he venture far ahead or stay at the edge of the light? Does he attempt to disarm a trap the moment he finds it, or go back to consult the party? In a fight, does he get stuck in with the others, hit and run, or look around the room for places to cut off reinforcements?
While you don’t control the loot you obtain from your adventures, magic items are as much a part of character growth in 1e as leveling and class features, sometimes more so. The magical items you obtain will help set your character apart mechanically. Many stories I’ve heard of thieves in 1e have made special mention of the fact they had Bracers of Defense for a high armor class or even Gauntlets of Ogre Power to have the strength to open doors and gates in the course of their scouting. Consider what loot you want to bid for from your adventures and, if possible, what magic to buy, as these things will help make the thief your own.
If your DM is using the Wilderness Survival Guide and/or the Dungeoneer’s Survival Guide, then like all classes your Thief can present a wide variety of expertise in survival proficiencies. The thief starts with the maximum (3) proficiencies to choose and gets new ones at a regular rate. While some proficiencies have an obvious benefit to the thief (Alertness, for example) there is plenty of room to pick proficiencies that make your thief unique.