The Hashishin
In the 12th and 13th centuries, the breakaway Shi'ite Ismaili sect found political and martial voice in the form of the Hashishin. As the Middle East convulsed during the Crusades, with invasions of Turkic conquerors from further east, the Hashishin — whose name allegedly comes from the order's penchant of indulging in hashish during certain ecstatic rituals — sought to resist both the Christian invaders landing on the shores of the Levant and the Turkic dynasties that lorded over much of the Arab world. Hassan-i-Sabah, pictured above, founded the order of the Hashishin at some point in the 11th century and raised its most famous castle of Alamut in what is now Iran. In what's now northwestern Syria, the Hashishin for a time even ran its own kingdom in the mountains, replete with a number of doggedly defended castles.
A Hashishin's skill with a scimitar was, in legend at least, unmatched. The order was also skilled in the art of stealth and made a habit of murdering political opponents through the decades. After all, the English language has the Hashishin to thank for the word assassin.