Rogue

The Rogue is a player class. Rogues are skilled thieves. Nethack says of them:

I understand the business, I hear it: to have an open ear, a       quick eye, and a nimble hand, is necessary for a cut-purse; a        good nose is requisite also, to smell out work for the other senses. I see this is the time that the unjust man doth thrive. <...> The prince himself is about a piece of iniquity, stealing away from his father with his clog at his heels: if        I thought it were a piece of honesty to acquaint the king withal, I would not do't: I hold it the more knavery to        conceal it; and therein am I constant to my profession. [ Autolycus the Rogue, from The Winter's Tale by               William Shakespeare ]

Strategy

 * Rogues have very low HP growth. Because of this, melee combat is dangerous. Rogues are better suited to fighting with ranged attacks; like crossbows, darts, and knives.
 * Rogues can easily resupply their ammunition by untrapping traps that shoot darts and arrows.
 * Darts make a good early game weapon, especially if they are dipped in the rogue's potion of sickness. Each poisoned dart does an additonal d6 damage to non-poison resistant monsters, and has a one in ten chance of killing it instantly.
 * Knives are an excellent early to mid-game weapon for rogues; because they can throw up to d4 daggers per round, depending on the character's skill. Knives are very plentiful in the Gnomish Mines, so they should never be in short supply.
 * Rogues give +d(XL) damage when striking a fleeing monster with a melee attack. Because of this, Elbereth and scrolls of scare monster are useful to rogues in close quarters.