- "You're the greatest trainer of Assassins in the entire Empire if not the world. There are wars going on throughout the continent and the Brotherhood needs you to aid them, not track down petty criminals!"
- ―William Lowndes to Omar, 1696.[src]
Training as an Assassin
Omar was born as the blind son of a butler in the household of Nigel Galloway in London. As a young boy, Omar met and befriended Rose Galloway, the daughter of Nigel Galloway, and the two remained close ever since. At the age of 12, Omar left the household after being recruited by the Assassin Brotherhood. By adulthood, he proved himself as a capable Assassin despite his handicap, training his other senses and putting his Eagle Vision to use, and eventually became a leader of a group of Assassins. After his father died, Omar did not return for the funeral. However, the Galloways ensured he was given a proper burial. 
At one point, Omar led his group of Assassins to a village, but failed to save its residents. This incident led Omar to return to London in an attempt to cope with the trauma he received. 
Apprentice under Isaac Newton
By 1696, Omar returned to London, entering the services of the scientist Isaac Newton, who served as the warden of the Royal Mint. With the increasing cases of counterfeiters in light of the Great Recoinage, Omar was contacted by his former fellow Assassin William Lowndes, who was the Secratary to the Treasury of Great Britain. William tasked Omar to contact Isaac, requesting his aid to investigate.
Omar eventually married a woman from London and had a son. After his son was born, Omar realised he wanted to help end slavery and supervised attacks on multiple slave owners. In 1703, Omar died during a raid in an attempt to free slaves upon a ship who were to be delivered to America. All 1,000 of the slaves aboard the ship survived.
- The name Omar (عمر) is a name of Arabic origin, mneaning "flourishing or long lived". Khaled is a variation of the Arabic name Khalid (خالد)), meaning "eternal, endless, or immortal".