The Shrieker is an undead enemy that appears in Leon Kennedy's campaign in Resident Evil 6. A mutated variant of the typical C-Virus-spawned zombie, Shriekers can be told apart from their regular counterparts by the enlarged lungs and larynx clearly visible on their bodies. Leon Kennedy and Helena Harper encountered several of these creatures during the Tall Oaks Bioterror Incident of 2013.
The Shrieker is a variant of the standard human-based C-Virus carrier, displaying the common traits of dead grey flesh in varying stages of decay. What sets it apart from other zombies, however, is that it sports grossly-enlarged respiratory organs which have expanded past the point of breaching the skin. This trait allows the Shrieker to emit a deafening scream which is capable of stunning prey when they are close enough. This screech also serves to attract other zombies, essentially 'ringing the dinner bell' as it were. Fortunately, the Shrieker's oversized respiratory system provides an obvious weak spot and gunfire will cause the sac to rupture, resulting in the Shrieker's death.
Shriekers behave in a similar fashion to regular zombies, with a few key differences. They are capable of walking and even running at a steady pace and move with more obvious intent, actively avoiding obstacles whereas standard zombies take no such care. They also possess a greater sense of self-preservation as they will attempt to flee when under attack. Like other zombies, Shriekers are driven by an insatiable appetite for living flesh. When attacking, they will get close to their victim before emitting a powerful screech that can leave a victim stunned and prone to attack.
In addition, when a Shrieker dies, it will emit one final scream in its death throes. Any zombies in the vicinity will also die as the scream causes their heads to explode.