King Boris is the self-proclaimed "King of Zombies".
After obtaining the Antibiotics from the Nursery and heading towards the gas station, a young girl begs for help over the Gamepad, saying that she and two others are trapped in St. George's Church with limited supplies. Despite the Prepper's protests, the Survivor heads to the Church. Upon arriving, however, they are ambushed and knocked unconscious by two men, Presumably Boris and an accomplice named Tim.
(He calls the Survivor the "offer" suggesting he may think the Zombies discriminate against people he deems unimportant)
It is revealed that "King" Boris has been capturing survivors and running them through a gauntlet where they must face a number of infected, solely for the entertainment of him and his numerous accomplices. He jeers at the Survivor's attempts to make it through, playing carnival music and taking on the personality of a deranged entertainer. This proves to be his downfall, however: the bright lights and loud microphone draw the infected to his location, and he and his cohorts are devoured. Before he dies, he yells "Do you know who I am?!", showing that he truly believes himself the ruler of zombies.
In the Multiplayer mode, one person plays as King Boris himself, and the other as a Survivor. He must be careful as he has limited zombies to deploy at a time, and the Survivor gets bonus items after killing enough of his minons. What Boris must do changes from mode to mode.
- In Capture the Flag, King Boris must use his Grunt Zombies to capture the flags will using his other zombies to stall/kill the survivor be he/she gets it. The round ends after 1 of the 2 reaches the win limit.
- In Kill mode, The king of zombies must kill the survivor, but he can't just place as many as he wants, as survivor earns points by killing them (making Explosive Hunters a very risky zombie) The round ends when King Boris kills the survivor.
- In Survival mode, King borris must kill the survivor ASAP to win. The round ends when the survivor is dead.