The Templars are a religious and political group in Dan Simmons's Hyperion Cantos, appearing in the novels Hyperion and The Fall of Hyperion.
The Templars are a cult of nature-worshipers who regard the nineteenth-century American naturalist John Muir as a prophet. They are headquartered on the planet God's Grove. The Templars' ideology exhorts them to preserve and spread life throughout the galaxy. A part of the Hegemony of Man, the Templars ply the spaceways in giant "treeships", organic starships grown in a manner similar to Dyson trees and capable of carrying thousands of crewmen and passengers over vast distances. Containment fields in the treeships maintain atmosphere and the passengers are placed in hibernation while the ship's Hawking drive is engaged. Slower-than-light movement of the treeship is achieved through the use of ergs, living organisms capable of manipulating gravitational fields.
In Hyperion, Het Masteen, a Templar and captain of the treeship Yggdrasil, transports the pilgrims to the planet Hyperion and joins them on their journey to the Time Tombs.
In The Fall of Hyperion, it is revealed that the Templars are in league with the Ousters, a race of genetically-engineered humans who live in deep space and oppose the TechnoCore and the Hegemony. The government of God's Grove prepares to greet an incoming fleet of Ousters they believe are participating in a coordinated invasion of the Hegemony. Unfortunately, the fleet inbound to God's Grove proves to be a TechnoCore fleet disguised as Ousters, and the planet is attacked and largely destroyed.
However, Templars continue to exist in various locales across the Milky Way galaxy, particularly at Ouster colonies where Templars are found in The Rise of Endymion. These colonies experienced the "Shared Moment" of humanity that ensued during the death of Aenea. In the short story "Orphans of the Helix", Templars are found living in an Ouster colony several centuries after the events of the Hyperion Cantos.