Reginald Birch

Reginald Birch (1705 - October 9, 1757) was the Grand Master of the British Templar Order. He is the true main antagonist of the novel Assassin's Creed: Forsaken (at least until the Assassin's Creed III tie-in chapters), where he trained the novel's protagonist Haytham Kenway to become a Templar and ordered Edward Kenway to be murdered.

Having been responsible for Haytham Kenway's rise within the Templar's ranks and gave many of his assignments to him, his motivation in truth was to get a hold of Edward's journal and find out about the Observatory, which he was once in (Assassin's Creed IV: Black Flag). His name was also in war letters in Assassin's Creed: Rogue.

Merchant-turned Templar
Reginald Birch was the son of a London merchant and became a wealthy merchant himself, eventually joining the Templar Order and rising to become the leader of the British Templars, he learned that the assassin Edward Kenway owned a journal that contained very valuable information on the First Civilization so in order to find it he befriended Edward, became one of his senior property managers and began courting his daughter Jennifer in order to be able to try and locate the journal, eventually Edward's young son Haytham unwittingly revealed the most likely location of the journal.

Assassination of Edward Kenway
Jennifer eventually discovers that Reginald is a Templar and tells her father which leads Reginald to quickly send mercenaries to attack the Kenway house, killing Edward, kidnapping Jennifer and stealing his journal, although Reginald arrives and saves Haytham from the mercenaries and invites him to join the Templars, offering to help him avenge his father and rescue his sister who he actually sold to Turkish slavers, Haytham accepts.

Precursor Site in America
Reginald eventually finds a scholar named Monica who would be able to decode the journal and kidnaps her, he also sends Haytham to kidnap her son Lucio who is also a scholar, likely for both decoding the journal and to use as leverage, forcing them to live in harsh conditions until they decode the whole journal. When the journal is decoded Haytham manages to discover the existence of a valuable First Civilization site in the colonies and sends Haytham there to establish a Templar presence there in order to locate the site.

"Justice is served" (Death)
Haytham had his friend Jim Holden search for Jennifer while he was busy with his work as a Templar, Jim eventually manages locate her in 1757 (22 years after she was kidnapped) and Haytham and Jim proceed to rescue her, Jennifer reveals that Reginald was the one who killed their father and sold her into slavery and the three of them proceed to attack Reginald's château in France, Reginald is then killed by Jennifer, who pushed him into a door with a sword in it.

Trivia

 * He was mentioned in several war letters in Assassin's Creed: Rogue, most of which mentioned his obsession with First Civilization technology. One also made mention of a warning that Birch would have Haytham go to the Thirteen Colonies and kill Achilles Davenport, and another shows how he wanted to recruit a scientist to the Templar cause.
 * Reginald's death was like that of Rodrigo Borgia's; both are murdered by their lessers and lieutenants (Cesare Borgia and Haytham Kenway) upon discovery of betrayal.
 * Reginald Birch only appears twice in Assassin's Creed III; when Haytham was to put down the Assassin Miko at The Beggar's Opera perfomance, Birch attended to give Haytham the mission, and again when the assassin plan succeeded, where he has Haytham go to the Thirteen Colonies by boat. He was mentioned very few times during Haytham's adventures in the Colonies, but once the game's perspective is shifted to Haytham's Assassin son Connor, he is never mentioned again, or seen. The fact that Haytham had betrayed Birch and let his sister murder him in Assassin's Creed: Forsaken might have something to do with that, but otherwise, his presence in the game is incredibly minor.
 * Birch was the second of three traitorous mentors who taught the protagonist how to fight in the Assassin-Templar War. The first was Al Mualim in Assassin's Creed and the third was Pierre Bellec in Assassin's Creed: Unity.
 * He resembles Francois-Thomas Germain, as they both wear similar clothes.