Rexford Kaylock

Rexford Kaylock (unknown – 1868) was a British Templar heading one of seven gangs aligned with his Order, which controlled all of London's boroughs around 1868.

The leader of the Blighters in the Whitechapel borough, he was at some point tracked down and assassinated by the Assassins, who sought to seize control of the gangs and take back the city.

Reference

 * Gamereactor.eu: Assassin's Creed: Syndicate, Sequence 3 gameplay demo