- "I am a navigator in the Sultan's navy, currently on leave to study cartography. But through my soldiering, I have also gained an appreciation for artillery and explosives. And it has served the Assassins well."
- ―Piri Reis, 1511.[src]
Haci Ahmed Muhiddin Piri (c. 1467 – 1553), more commonly known as Piri Reis for his legendary stature in the Ottoman Navy, was a famed admiral and cartographer.
Unknown to most, Piri was also a member and a Master Assassin of the Ottoman Brotherhood of Assassins. Though not involving himself in missions of violence, Piri served the Assassins as a technician, primarily providing them with materials and methods for crafting bombs.
- "For ten months I have been working on a new map for Bayezid. But he is old, and I am a perfectionist... Perhaps the next Sultan will appreciate my efforts."
- ―Piri speaking of Sultan Bayezid II.[src]
Piri was born in Gallipoli, Ottoman Empire, and became a seafarer from a young age. By his early teens, Piri traveled as a privateer with his uncle Kemal, with whom he completed several expeditions in and around the Mediterranean; though their work was described to be of "dubious legality."
Eventually, by the time Piri was in his twenties, he and his uncle turned to a more respectable trade, and joined the naval forces of Sultan Bayezid II. As a navigator in the Ottoman Navy, Piri fought in the Ottoman–Venetian War from 1499 to 1503, losing many friends in the fight.
In 1503, after the war had ended, Piri decided to halt his military adventures, and took a leave from the navy. He resided in Constantinople in order to shift his interests to a more intellectual area, setting up a small studio in the Grand Bazaar, where he began to study cartography.
That same year, a group of Italian Assassins sent from Rome to Constantinople by Ezio Auditore infiltrated Piri Reis' shop to steal some of his maps detailing the New World, in order to match the Templars' expansion into the new lands.
- Ezio: "We fight to end the fighting. It is a sad irony."
- Piri: "It will always be an irony, evet (yes). But perhaps one day it will not be so sad."
- ―Ezio and Piri, regarding the Assassins' motives.[src]
Despite his earlier conflict with the Assassins, Piri joined the Ottoman Assassin Brotherhood in 1506 to serve as a scholar and technician, and even eventually progressed to the rank of Master Assassin.
Having witnessed and grown tired of the many artificial boundaries that had divided the nations he had traveled to, Piri was drawn to the Assassin philosophy, which he saw as the "truest intellectual freedom."
Using his experience as a sailor, Piri invented specialized bomb variants and casings, all specifically for the Assassins' use. These he offered for a price at his workshop, given that those who wished to buy them were willing to learn how to use them first.
In 1511, Piri heard of Ezio Auditore's arrival in Constantinople from Yusuf, and met the Mentor himself shortly afterwards. Yusuf had directed Ezio to Piri to ask for directions to the trading post of Niccolò and Maffeo Polo, which Piri readily gave. The cartographer also introduced Ezio to the variety of bombs he had for sale, as well as offered to instruct him in their use.
Over time, as the Assassins Guild completed contracts all over the Mediterranean, Piri would periodically ask for their help in surveying the region, in order to aid in his cartography efforts. Additionally, when any new city came under the control of the Assassins, Piri would receive special bomb ingredients from the region, and place them for sale in his Grand Bazaar shop.
Ezio discovered the delivery of several firearms to equip the Byzantine Templar army, and reported his findings to Prince Suleiman I. Suleiman ordered Piri to bring Ezio safely to Derinkuyu, where the Templars' headquarters was located.
Despite the Janissaries' attempts to stop any ships from leaving by raising the Great Chain across the Golden Horn, Ezio managed to destroy it with a bomb that had "fifty times the kick of [the Assassins'] regular bombs", and set the Ottoman fleet ablaze with Greek Fire. Piri only commented on Ezio's less than subtle approach, before setting sail.
After arriving at Cappadocia in 1512, Piri awaited Ezio aboard his ship, as the Mentor set off to kill the Byzantine heir and Templar Manuel Palaiologos, and to retrieve the last of the Masyaf Keys. After Ezio had succeeded, setting much of the underground city into chaos after destroying their armory, he returned to the ship, which Piri directed back to Constantinople.
By 1513, Piri continued his work as a cartographer, and produced what would come to be known as his most famous map, which contained one of the earliest, accurate depictions of the eastern shore of South America. By the time he was 80, Piri had become a legend in the Ottoman Navy, and was officially granted the title of "Reis" or "Admiral."
Personality and characteristics
- Ezio: "Piri Reis? I think I have seen some of your earliest work."
- Piri: "Reis? Did Yusuf Tazim send you? That sounds like one of his exaggerations."
- ―Piri, regarding his title as "Reis," 1511.[src]
Piri was an intelligent and witty man, who would appear disgruntled if interrupted. He was a self-proclaimed perfectionist, who initially felt that his drafting skills were under-appreciated by his patron. Regardless, he was described to be a man of "rare artistic and technical talent."
Piri was a close friend of Yusuf, whom he spoke with regularly. Yusuf thought quite highly of him, referring to him as "Reis" forty years before he had even officially received the title.
- Christoffa Corombo's atlas contained one of Piri's maps, which Ezio recovered from the Templars.
- In one of Abstergo Industries' dossiers, it was speculated that Piri's map of Europe was secretly a map of Isu Temples.
- Piri Reis believed in heliocentrism, regarding geocentrism as "a bunch of horsepiss". 
- Assassin's Creed: Revelations (first appearance)
- Assassin's Creed: Revelations novel
- Assassin's Creed: Project Legacy (mentioned only)