The Blighters were a 19th century gang affiliated with the Templars in London. Led by Maxwell Roth and his seven lieutenants, it was the principal organ by which the British Rite operated in the capital in that period, essentially being a criminal syndicate which informally supervised each of the London boroughs through coercion.
At its peak, the Blighters dominated virtually every industry and every class in London overtly or from behind-the-scenes; its reach was no longer confined to the impoverished lower class. They became the soldiers of Templar agents and, aside from their frequent murder of opponents, forced children to perform dangerous labor in their factories against regulations. Through their brutal actions, they became loathed by common Londoners as a blight on their city, worse than even the petty gangs which preceded them and engaged in rampant gang wars.
In 1868, the syndicate was at the height of its power, its domination of London entirely uncontested save for a lone remaining Assassin bureau leader, Henry Green and the gang called Clinkers. That same year, the Assassin twins Evie and Jacob Frye arrived in London and took over the Clinkers, renaming them as the Rooks, a rival syndicate created to wrest control of the London underworld away from the Blighters. Over the course of the year the tide was turned against the Blighters, and by year's end they were extinguished as a noteworthy force along with their Templar masters.
In the mid-19th century, the British capital city of London was severely plagued by violent crime throughout its impoverished districts. Common people among the lower-class, adapting to the adverse environment, tended to form communities in an appeal for unity of the downtrodden throughout the country. Nonetheless, these communities gave rise to rival gangs which did not shy away from violence to exert dominance.
Seeing the potential in these gangs to serve as his base of power, the Templar Grand Master of the British Rite, Crawford Starrick, hired the infamous criminal, Maxwell Roth, with an extraordinary sum of money to establish a syndicate of their own. Roth used his expertise to train seven hand-picked Templars to lead the divisions of what became the Blighters. The network he had built up over his years provided him and Starrick with the resources they needed to expand their gang and recruit henchmen, a task that nonetheless took a decade to be fully realized as a significant force to be reckoned with.
The Blighters began their work in Westminster's worst slum, Devil's Acre, and quickly spread their reach from there until they consumed all of London. Initial hopes that the Blighters' monopoly on crime would prove to be the solution to the incessant chaos of gang wars were dashed when the syndicate proved to be an even greater source of terror for everyday people. Quickly, they developed a notorious reputation for wanton destruction, mercilessness, and ruthlessness, loathed by Londoners as a tyrannical underworld regime. They extorted money from businesses, ran factories which operated solely on children forced into service with little to no pay and forbidden from returning home, and murdered those who opposed them.
By 1868, the Blighters, and the British Rite of the Templars with them, controlled virtually every industry, every class, every borough, and every petty gang in London, their influence no longer limited only to the lower class. The Metropolitan Police Service was hard-pressed to fight their dominance, and even the Assassin Council of the British Brotherhood of Assassins had abandoned the city, leaving one obstinate agent behind, Henry Green, who continued to supervise their bureau.
Downfall by the Rooks
That same year, however, the Blighters suddenly collapsed in the face of a new challenge: the Rooks. The new gang, founded by the Assassins Jacob Frye from among the remaining resistance offered by the Clinkers, worked with the Metropolitan Police Service and eroded away at the power of the Blighters. Factory by factory, stronghold by stronghold, Jacob and his twin sister Evie freed the Blighters' child laborers, destroyed their bases of operation, assassinated or arrested their Templar agents, and defeated them in open street warfare. Ineffectual at stopping the twins' precipitous rise, the Rooks siphoned more and more resources from the Blighters, as more and more of the Blighters' own gang members defected to the Rooks.
All seven of the Blighter leaders were killed in gang fights led by Jacob and Evie, and their foundations were further crippled when even their Templar masters were assassinated. Roth was assassinated by Jacob in a dramatic confrontation at the Alhambra Music Hall which burned down the theatre, and Starrick was slain by the twins in the Buckingham Palace vault during a ball hosted by Queen Victoria. Before the year was out, all seven boroughs of London had been seized by the Rooks and their Assassin leadership, and the Blighters were all but eradicated from the city.
Despite their destruction, the Rooks that replaced them comprised of many former Blighters, choosing to defect. While the Rooks had to abide by their Assassin leaders' norms and did not practice child labor, they remained susceptible to corruption. Two decades later, the rogue Assassin Jack the Ripper managed to seize control of the Rooks and turn them into his agents as he committed serial killings across London. Through Jack's actions, the Rooks became no different from the Blighters they had dislodged.
On the other hand, remnants of the Blighters were still active and loyal to the Templar Order by 1872 and lasted until 1916. 
Although they were not professional soldiers, the Blighters were the closest thing to the British Rite's militant arm in London in the latter 19th century. In contrast to their earlier predecessors which managed to influence the British Army and the East India Company, the British Rite relied on these henchmen who were little more than common thugs which did their bidding. Even so, their crime syndicate monopolized power in the city's underworld and dominated every industry and sector of society through violence and coercion until their sudden collapse to the Assassins' rival gang, the Rooks, in 1868.
The Blighters were organized into typical roles. Common street fighters of average size were "soldiers" whereas "brutes" were the heavy-weight, muscular thugs; they carried little more than a pocket knife and a butcher knife respectively along with a pistol. "Watchers" were snipers standing atop rooftops with their rifles, "enforcers" were more versatile fighters trained in the use of flash bombs, and "lookouts" were unarmed criminals whose only job was to sprint for reinforcements at the first sign of trouble. Among these thugs, only the "protectors", clad in heavy trenchcoats emblazoned with the Templar insignia, were ever of any trouble for Assassins; these were trained combatants who were better equipped than the run-of-the-mill henchmen, brandishing cane-swords instead of crude knives.
- Rexford Kaylock, in the Whitechapel borough
- Cletus Strain, in the Lambeth borough
- Edith Swinebourne, in The Thames borough
- Octavia Plumb, in the Southwark borough
- Bloody Nora, in the City of London borough
- Victor Lynch, in The Strand borough
- Lilla Graves, in the Westminster borough
- Harvey Hughes
- David O'Donnell
- Ivan Bunbury
- Maude Foster
- George Scrivens
- Simon Chase
- Leopold Bacchus
- Jesse Butler
- Mildred Graves
- Emmet Sedgwick
- Sylvia Duke
- Albie Vassell
- Gilbert Fowler
- Milton King
- Anna Abramson
- Homer Dalton
- Harrison Harley
- Wade Lynton
Behind the scenes
- Assassin's Creed: Syndicate (first appearance)
- Assassin's Creed: Last Descendants – Locus
- Assassin's Creed: Odyssey (simulated ship crew)
- Assassin's Creed: Syndicate
- Assassin's Creed: Syndicate – Database: The Blighters
- Assassin's Creed: Syndicate – Database: Maxwell Roth
- Assassin's Creed: Syndicate – To Catch an Urchin
- Assassin's Creed: Syndicate – Somewhere That's Green
- Assassin's Creed: Syndicate – Final Act
- Assassin's Creed: Syndicate – A Night to Remember
- Assassin's Creed: Syndicate – Database: Jack's Gang: The Rooks
- Assassin's Creed III
- Assassin's Creed Chronicles: India
- Blighter on Wiktionary
- Assassin's Creed: Odyssey