One of the first professions to arise in history as people became more civilized, many races lay claim to the original thieves. It is likely that there is no real answer to the question; the earliest srryn were just as inclined to be picking pockets amongst their huts as the aelin swindled each other in the shadows of their growing cities. The nefortu, ever fond of their tricks, as well took to this work as they emerged, and the shuddeni too enjoy such exploitation of others. Even the ch'taren have taken to these roguish practices, using them to subtly work a greater good upon the world.
Above all other weapons, thieves specialize in daggers, using them to slice and stab at foes, often inflicting unparalleled amounts of damage with them. They do also learn to use swords, and occasionally utilize whips as well; the former to better defend themselves. Most thieves learn swiftly the benefit of rapidly shifting their weapons about. Thieves have also developed their own method of communication through complex hand gestures, known as cant.
Coming from all walks of life, thieves may be of any alignment and may follow any god or none; even Iandir and Jolinn have welcomed the faith of thieves who apply their copious talents in appropriate ways. Among aelin thieves, Serachel is often the source of many a swift prayer, as his dominance over shadows places much of their work under his aegis.