Cyberdemon

The Cyberdemon is perhaps the most formidable enemy in classic Doom (although the Spider Mastermind is often a greater threat to the player due to her hitscan weapon). He first appears as a boss at the end of Doom level E2M8, and re-appears in the secret level E3M9, and also on E4M2, E4M6, and E4M7. The Cyberdemon also appears on the retail box cover of Doom II, and is used sparingly throughout that game.

The Doom II manual describes the monster as follows:

''The Cyberdemon: A missile-launching skyscraper with goat legs. 'Nuff said.''

The Cyberdemon is not listed in the PC Doom I manual, presumably to make its climactic appearance in E2M8 a surprise. The SNES manual for Doom I does however mention of the Cyberdemon:

''Cyberdemon: Half unfeeling machine, half raging horned devil. This walking nightmare has a rocket launcher for an arm and will definitely reach out and touch you. Make sure you're loaded for bear before you get to this guy.''

Combat characteristics
It attacks by firing barrages of three rockets. It has 4000 hit points and does not receive splash damage from explosions, making it fairly difficult to kill. It is also the fastest moving monster in the original game, and third fastest in Doom II(after Archvile and Revenant).

Cyberdemon rockets behave exactly as the player's rockets, although they cannot damage other Cyberdemons. Furthermore, the Cyberdemon and the Spider Mastermind take only direct hit damage, and are immune to all blast damage. Therefore, a greater number of rockets is required to kill these bosses than might be expected, and they must be direct hits. The Cyberdemon is given a higher probability of performing his missile attack than other monsters, causing him to launch volleys of rockets at a high frequency. The Cyberdemon does not have a melee attack. In common with other monsters, although the Cyberdemon is shown with his rocket launcher in his left hand, the rockets emerge from his middle.

Tactical analysis
The BFG is the most effective weapon against a Cyberdemon, although the plasma rifle can work fairly well. Because a Cyberdemon has a low pain chance, it is difficult to prevent it from attacking. It is also important to be constantly aware of when it fires a rocket, as it will do so relentlessly. Strafing is the best method for avoiding rockets.

Because one rocket will often be enough to critically injure the player, it is imperative that all rockets are avoided. Because of splash damage, it is also important to stay away from the explosions. For example, it is advisable to avoid standing too close to a wall when fighting a Cyberdemon, as splash damage can be sustained from rockets hitting the wall.

Killing a Cyberdemon
Killing a cyberdemon can be very easy once you know its weaknesses. One of them is it's immense size. In certain maps in doom 2 such as level 21: nirvana. The cyber demon(s) are in a large courtyard or structure and the entrance is too small for them to go through. Which can give a novice player the chance of escape incase of major injuries. Avoid close range fighting if possible. there is only one way to kill a cyberdemon in close range...as hilarious as this sounds but, when attacked at the feet with a chainsaw they seem to have a higher pain chance and cannot reach you with the rocket launcher because of being so close. The Cyberdemon AI is programmed to run away in cases such as this so only attempt this technique in a small space or to draw hits from imps or revenants to provoke major monster infighting. This is a great idea because of the huge amount of splash damage that the cyberdemon uses. Note: this technique doesnt work on other cyberdemons or arch-viles considering that Cyberdemons are immune to their own rocket shots and dont take splash damage from anything. the arch-viles will but dont shoot back from other monster shots.

Killing a cyberdemon is almost impossible without almost full rockets,cell weapons,shotgun shells ( if your that desprate ) and chaingun clips. The easiest way to kill the cyberdemon is with the BFG9000. It may eat up 40 cells in one shot but three to four direct hits will kill a cyberdemon and (possibly) damage other targets in the room. If you dont have that kind of firepower (or couldnt find the ammo) resort to the rocket launcher if you can. about thrity-five well placed hits with the rocket launcher will kill a single cyberdemon (Killing the cyberdemon with anything else is hard for even the most hardened doom players.) If your the chump who either A.died on the first try of killing a cyberdemon ( and lost all of your ammo) or B. was stupid enough to start on a map with one or more cyberdemons you may want to consider starting a level earlier because it takes about one thousand shots with a chaingun to kill a cyberdemon.Shotguns... well I don't know about the numbers there, but it takes a really hardened doom player or a complete jackass noob, to get lucky enough to kill a cyberdemon with a shotgun. ( please don't try it..I don't know how to pull that off) Anyways always remember to circlestrafe when attacking one or more of these bad boys. The run speed in doom 2 is amazingly fast and as long as your not in acid or lava criclestrafing can save you a buttload of hard work and getting your ass kicked a billion times by the amazingly strong cyberdemon rocket launcher.

Appearance statistics
The IWADs contain the following numbers of Cyberdemons:

Doom RPG
In the Doom RPG, the Cyberdemon was created by evil mastermind Kronos, by combining human technology with demon flesh.

Non-Doom games
Cyberdemons are also found in the Roguelike game ZAngband and many derivative games, such as Gumband, Hengband and ToME. There they have similar characteristics to Cyberdemons in the Doom series, although they have been given a tremendously strong close-combat attack (four strokes for 150 damage each) in addition to their traditional rockets. Also, the unique monster Oremorj the Cyberdemon Lord can be found in Zangband and Hengband (Oremorj is Jromero, i.e. John Romero, read backwards).