The Screamer was a prototype for Special Infected formulated early in Left 4 Dead's development. As such, he is the progenitor of Special Infected like the Witch and Boomer. Screamers were presented in-game as Infected humans bound in a restraining psychiatric-style straitjacket.
The idea for the Screamer was for him to lurk in different areas, much like the Witch, paying no attention to his surroundings until coming in contact with a Survivor whereupon, if sufficiently agitated, he would run away from Survivors in an attempt to hide. If he succeeded in escaping, he emitted a loud scream that alerted a horde, causing an attack - thus, foreshadowing the later Boomer bile concept, and additionally helping to establish early on in production that the Common Infected are driven to extreme aggression as a response to loud noises. It was therefore important for the players to kill the Screamer before he could escape and call a horde. Since the Screamer was under physical restraint, he did not have the ability to mount any direct attack on Survivors.
As stated in the Developer Commentary, Screamers and Boomers co-existed for a time during development. At the time, the Boomer merely exploded when killed, causing damage to nearby Survivors, while the Screamer would attract hordes with his scream. Ultimately, the Screamer was cut from the game because he was deemed too difficult and confusing for the Survivors to spot and track down amongst a crowd of Common Infected. However, the idea of a Special Infected having an attack that attracts a horde was considered too good to go to waste, and the Boomer was then given its bile attack and its bile splash death effect.
- The Screamer serves as the progenitor for the Hunter, Witch, the retail version of the Boomer, and the Jockey, as well as the Fallen Survivor. His screams were recycled as the warning for a Hunter's pounce attack. He stood idle in place until alerted, which later was an attribute given to the Witch. His screams attracted horde attacks, like the retail Boomer's bile attack, and he cackled maniacally, like the Jockey, who is also speculated to have been insane prior to infection. The Fallen Survivors run away from Survivors, much like the Screamer, in an attempt to escape.
- The straitjacket is usually used as a restraint to prevent mental patients from harming themselves and others. Since the Screamer is bound in a straitjacket, it hints that the Screamer was formerly either a mental institution patient or an early on-set Infection victim restrained due to the disease's crazed symptoms.
- The Screamer bears a resemblance to the Siren in the game Killing Floor. Both wear straitjackets and scream. It could also be viewed as resembling the Lying Figures from Silent Hill 2, who run in straitjackets made of their own flesh and spit out bile acid.
- Another resemblance is seen in the zombie survival game "State of Decay", where zombies sometimes called "Screamers" are seen, with their arms removed at the shoulder, and they attract other zombies via screams.
- Judging from concept art, the Screamer has the same shoes as the Hunter.
- There are no existing screenshots or models of the Screamer other than its concept art. However, a mod has been made recently that replaces the Boomer with a fanmade model of the Screamer, as well as some other attributes.
- In old reslists files the Screamer can be fully referenced with a model and materials. This was merely a placeholder, and the Screamer never actually had a model.
- In the Xbox 360 version of Left 4 Dead, there's a test CFG file for the Screamer to spawn him, he's referenced as the Scout in the config's name, but in the config itself he's referenced as the Screamer. 
- In addition, a folder named classes exists there, inside which the Screamer can be referenced, he was a playable character once in development. The header references the Boomer file in the same folder.
- In various talker files in both the main game and the DLC The Sacrifice the Screamer can be referenced.
- In the 2006 Trailer for Left 4 Dead there's a Hunter scream that can be heard, at first glance one would think they just put a infected sound there to be the reason of triggering the horde, but it's actually the Screamer being referenced. This is most likely the last time the Screamer was in the game.
|Introduced in Left 4 Dead||Introduced in Left 4 Dead 2|
|The Boomer||The Hunter||The Smoker||The Tank||The Charger||The Jockey||The Spitter|
|Introduced in Left 4 Dead||Introduced in Left 4 Dead 2||Cut Infected|
|The Witch||Common Infected||Uncommon Infected||The Screamer|