Now that Stallone is recutting Rocky IV, it's a good time as any to ask for the X cut of Cobra to be restored and released! 

The first rough cut was over two hours long (the closest estimated original running time is 130 minutes). It was then shortened to a roughly two-hour director's cut which was intended to be released in theaters. However, after Top Gun became a smash hit, Stallone and Warner Bros. were worried that Cobra - which would premiere the following week - would be overshadowed, so in order to ensure at least one extra screening each day the movie was heavily re-edited. Stallone removed much of the plot and scenes involving characters other than his own. Warner Bros. also demanded that the more graphic scenes be cut down or removed entirely because they were "too intense," and that some action scenes be cut for pacing.

When first submitted to the MPAA the film received an X rating, necessitating even more cuts. The full extent of the censorship is unknown, but based on director Cosmatos's commentary and several other sources, some of the cut scenes include:

The first murder victim having her throat cut and hands severed;
An Asian American child delivers a wrapped present to the LAPD office as instructed by one of the members of the New World. As the officer tells the child to stay, he proceeds to unwrap the present only to discovers traces of blood coming from the box. The officer answers a phone call from one of the members of the New World, who speaks a cryptic message of the murder victim's hands inside the box;
More dead bodies in the autopsy scene, including lingering shots of naked and mutilated bodies of murdered women;
The New World's day jobs as welders, carpenters and fish market employees and cleaners, which were originally part of the "Angel of the City" sequences. These were cut and replaced with the scenes of the New World doing a routine workout ritual as seen in the film's opening;
An extended death scene for Ingrid's photographer Dan, in which he is hit several more times with axes and attempts to escape, only to slip on his own blood and fall down in puddle of it before being finished off with even more hits;
The scene in which the Night Slasher tries to kill Ingrid in the hospital was cut down for pacing and content. The deaths of the janitor and nurse were originally shown onscreen and a scene where a police guard outside Ingrid's room is killed by the Night Slasher was also cut. A later scene where Cobretti mentions the officer's death to Monte was cut to maintain continuity, which as a result made the editing of that scene choppy;
More scenes of the townspeople (including the motel owner and diner waitress) being killed during the climax, including a scene in which one is hit in the face with ax; two of these death scenes appeared in 1990's TV versions of the film, but with most of the more graphic shots removed;
Graphic close-ups of the Night Slasher's wound after he is impaled on the hook; Cobretti repeatedly forces the hook deeper into the Night Slasher as he screams in pain;
After the demise of the Night Slasher, Cobretti and Ingrid leaves the factory but before they can exit, countryside police enter wherein the sheriff demands from them of what took place in the factory.
Besides these cuts, a few scenes in which the Night Slasher and his gang are killing people were slowed down (for continuity reasons since demanded cuts made the editing of the scenes look choppy), while some of the shootouts which were originally in slow-motion were instead played at normal speed (in order to cut prolonged death scenes of gang members, plus close ups of many bullet holes which were also cut).

Eventually, the movie received an R rating and was released in theaters with a running time of 84 minutes, approximately 50 minutes shorter than the first assembly cut and 30 to 40 minutes shorter than the director's cut.