Brzak was a human-based B.O.W. created by the C-Virus. It was encountered by Leon and Helena within the depths of the ancient Catacombs that lie under the Tall Oaks Church. It's name is derived from the Serbian word for "Rapids".
The Brzak appears to be an oversized bull shark, though it was of human origin. It appears to be blind as it was not impaired after being struck in the eyes with a harpoon, and presumably it uses electroception to navigate, as other predatory sharks do. Its tongue is vastly deformed, boasting a bright orange extension covered in bony protrusions, and takes up a large portion of the creature's head. This tongue appears to be capable of extending to ensnare its victims. The creature's fins appear to end in claws, which enable it to navigate rough terrain and pursue its prey through not entirely aquatic environments.
According to its file, the Brzak was one of the Family's experiments with the C-Virus. The Brzak was used by the Family to dispose of dead test subjects, due to its predatory instinct to hunt down and eat anything that moves in the water. Before the Tall Oaks Bioterror Incident, Derek C. Simmons ordered his men to release the Brzak from its aquarium should anyone break into the Family's hideout.
The Brzak was first encountered when Leon and Helena tried to escape the underground facility under the church. They quickly saw a disturbance in the water, noticing the large fin splashing around. The B.O.W was trapped behind underwater rubble, allowing Leon and Helena to escape. The Brzak eventually manages to sneak up on Helena and pull her underwater, only escaping after a fierce struggle.
After the duo are trapped in underwater ruins, the Brzak stalks them as they swim for air. It catches Helena and Leon is forced to climb up onto its back to help her. They gouge out the creature's eyes, successfully forcing it away. Leon encounters it again while swimming to safety and must narrowly avoid its attempts to pull him underwater.
The Brzak swims after the two when they fall into an underground waterfall and they are forced to shoot its mouth to keep it at bay. The Brzak was killed when Leon (or Helena) shot an explosive barrel flying above them, sending shockwaves and shrapnel into the creature's open mouth.
The First encounter with the Brzak is a series of Quick-time-events that differ slightly depending on whether the player is using Leon or Helena, although the cutscene ends with the characters trapped in an underground cavern regardless. Both characters must reunite by the iron gate on the other side of the water but this is complicated by the return of the Brzak. Leon must rapidly hammer the action button to swim away from the beast whilst Helena fires at its glowing tongue. Failing to do so will result in a game over. Once both characters are on dry land, interact with the gate to trigger the final encounter.
The Brzak knocks Leon and Helena into an underground waterfall and begins advancing towards them. The Player must fire at its glowing tongue to drive it back or they will be killed instantly when it devours them. After shooting at the beast for several moments, another quick-time-event is triggered and failure will result in another immediate death. Explosive barrels will start falling down the tunnel and the game will go into slow motion. Aim and shoot the barrel above the Brzak to finally destroy the monster.