- "I'll send you the driver. We've trained him with PE2 in our labs, he shouldn't be any trouble."
- ―A member of Abstergo Industries in a letter to an associate.
William Greer (22 September 1909 – 23 February 1985) was an agent of the United States Secret Service, best known for having driven President John F. Kennedy's automobile in the motorcade through Dealey Plaza in Dallas on November 22, 1963, where the president was assassinated.
William Greer was used as an agent by Abstergo Industries. Having been trained using "PE2", his orders were to steal Kennedy's Piece of Eden in the chaos immediately following the assassination. He was also assigned to slow the vehicle down so Lee Harvey Oswald or the second shooter could easily take the shot on Kennedy.
- Assassin's Creed II (mentioned only)