The Knights Templar was a prominent monastic order in the 13th century in Europe. Centuries after their trial, the Templars still have the interest and the curiosity of historians.
However, they were not the only military order which was active at the time. The Christian society of knights is comprised of several orders which came to light in the Middle Ages. They shared principles and beliefs such as dedicating their time and effort to protect Christian pilgrims coming to the Holy Land. Also, most of their members took vows of chastity and poverty and abided by their order's rules and regulations. Besides the Knights Templar, here are the original orders of the Crusaders.
The Knights Hospitaller is a monastic order that rose in the 12th century. They were the knights of Saint John Hospital in Jerusalem. They were tasked with providing help to those in need. The order is still publicity active and goes under the anime of the Sovereign Military Order of Malta.
The Order of Santiago: It started in Spain, intending to protect Christendom and fight off the Muslim Moors from Iberia. The membership was restricted to the Nobles. Unlike the Templars, who the king abolished, Juan Carlos restored the order of Santiago as a civil association of nobility and honor. Today, it remains as such.
The Order of Calatrava: it is one of the four Spanish military orders, next to the order of Santiago. It started in the 12th century and received gained the Pope's approval over the years. Most of its power was debauched by the 15th century, but they remained active till two centuries ago.
The Teutonic Knights: It started in Acre, Jerusalem saving the same purpose as the Knights Templar. Since 1810, the order is no longer involved in military actions. Till today, the Teutonic Order still offer honorary knighthoods.