The Poor Fellow-Soldiers of Christ and of the Temple of Solomon (Latin: Pauperes commilitones Christi Templique Salomonici), commonly known as the Knights Templar, the Order of Solomon's Temple (French: Ordre du Temple or Templiers) or simply as Templars, were among the wealthiest and most powerful of the Western Christian military orders and were prominent actors in Christian finance. The organization existed for nearly two centuries during the Middle Ages. Officially endorsed by the Roman Catholic Church around 1129, the Order became a favored charity throughout Christendom and grew rapidly in membership and power.

Templar knights, in their distinctive white mantles with a red cross, were among the most skilled fighting units of the Crusades. Non-combatant members of the Order managed a large economic infrastructure throughout Christendom, innovating financial techniques that were an early form of banking, and building fortifications across Europe and the Holy Land. The Templars' existence was tied closely to the Crusades; when the Holy Land was lost, support for the Order faded. Rumors about the Templars' secret initiation ceremony created distrust, and King Philip IV of France, deeply in debt to the Order, took advantage of the situation. In 1307, many of the Order's members in France were arrested, tortured into giving false confessions, and then burned at the stake. Under pressure from King Philip, Pope Clement V disbanded the Order in 1312.

The abrupt disappearance of a major part of the European infrastructure gave rise to speculation and legends, which have kept the "Templar" name alive into the modern day. After the First Crusade captured Jerusalem in 1099, many Christians made pilgrimages to various Holy Places in the Holy Land. However, though the city of Jerusalem was under relatively secure control, the rest of Outremer was not. Bandits and marauding highwaymen preyed upon pilgrims who were routinely slaughtered, sometimes by the hundreds, as they attempted to make the journey from the coastline at Jaffa into the interior of the Holy Land. In 1119, the French knight Hugues de Payens approached King Baldwin II of Jerusalem and Warmund, Patriarch of Jerusalem, and proposed creating a monastic order for the protection of these pilgrims. King Baldwin and

Patriarch Warmund agreed to the request, probably at the Council of Nablus in January 1120, and the king granted the Templars a headquarters in a wing of the royal palace on the Temple Mount in the captured Al-Aqsa Mosque. The Temple Mount had a mystique because it was above what was believed to be the ruins of the Temple of Solomon. The Crusaders therefore referred to the Al Aqsa Mosque as Solomon's Temple, and from this location the new Order took the name of Poor Knights of Christ and the Temple of Solomon, or "Templar" knights. The Order, with about nine knights including Godfrey de Saint-Omer and André de Montbard, had few financial resources and relied on donations to survive. Their emblem was of two knights riding on a single horse, emphasizing the Order's poverty.

The impoverished status of the Templars did not last long. They had a powerful advocate in Saint Bernard of Clairvaux, a leading Church figure, the French abbot primarily responsible for the founding of the Cistercian Order of monks and a nephew of André de Montbard, one of the founding knights. Bernard put his weight behind them and wrote persuasively on their behalf in the letter 'In Praise of the New Knighthood', and in 1129, at the Council of Troyes, he led a group of leading churchmen to officially approve and endorse the Order on behalf of the Church. With this formal blessing, the Templars became a favored charity throughout Christendom, receiving money, land, businesses, and noble-born sons from families who were eager to help with the fight in the Holy Land. Another major benefit came in 1139, when Pope Innocent II's papal bull Omne Datum Optimum exempted the Order from obedience to local laws.

This ruling meant that the Templars could pass freely through all borders, were not required to pay any taxes, and were exempt from all authority except that of the pope. With its clear mission and ample resources, the Order grew rapidly. Templars were often the advance shock troops in key battles of the Crusades, as the heavily armored knights on their warhorses would set out to charge at the enemy, ahead of the main army bodies, in an attempt to break opposition lines. One of their most famous victories was in 1177 during the Battle of Montgisard, where some 500 Templar knights helped several thousand infantry to defeat Saladin's army of more than 26,000 soldiers.