Alien: The Giler and Hill's Alien - Hercules, Genghis Kahan and Attila the Hun vs Jack the Ripper script?

Leading from
Alien: Pre-Production
and
Alien: Script Rewrites

a) David Giler the producer, continued to rewrite the script numerous times over the Spring, rewriting until there was little resemblance to the original and he did not want Dan O'Bannon's involvement. 

Ron Shusett revealed in interviews extra information about various drafts of Alien that David Giler and Walter Hill wrote that went to extremes and during this time it was as if the alien ship, its alien pilot's remains and the egg silo were disappearing or being totally transformed beyond recognition in pursuit of Hill and Giler's need for their sense of realism

depiction of Attila the Hun

b) In one description of the different drafts, the crew of the Nostromo would have the ability to call people from the past to fight the alien. In one instance they would call Hercules to fight the Alien and another instance they would call Genghis Kahn to fight the alien. 

In another description of the different drafts, the crew would be brought to fight past monstrous villains from history such as Attila The Hun and Jack The Ripper. 

As pointed out by the Ask Mr Kern radio program, the plot sounded more like the "Savage Curtain" episode of Star Trek.

depiction of Genghis Khan

Source Quotes

1. Dennis Fischer: Are they doing , without too many changes, your original script?
   Dan O'Bannon: Well, David Giler, who is one of the producers, sat down and just kept rewriting it all Spring, and just kept rewriting it, and rewriting it, and rewriting it 'til there was very little resemblance to the original screenplay, and then I wasn't allowed to participate in that because he didn't want me to. He was producer.  (Rocket Blast's comic Collector, no.148)
2. Ron Shusett: Regarding Giler and Hill, they did eight various drafts. And they went off in many different directions and so there were as different, I can’t even describe how many, so it was almost a different story many times. But it kept getting closer and closer back to the original cos the director kept thinking he liked the original better. For example, instead of the space jockey, they one time thought it would be, it looked like a futuristic bunker just made out of concrete and plastic and futuristic plastic and it looked like some advanced race had a war there. That was one idea they had. And so that you wouldn’t have that, replace that scene. Another idea they had let’s go really far out there, let’s have the ability to call people from the past to fight the alien. They would call Hercules or and it was ridiculous and everybody was laughing, ok this doesn’t work. They were trying, roping, you always have to see how far you can push the envelope. It got ridiculous when you got Genghis Kahn to fight the alien. So you can see how far apart it got. And then it got closer and like that bunker, but less spectacular. So they tried every level through eight drafts making it more outlandish to make it more realistic, but Ridley kept coming back to the structure we had which was working superbly in every way and they wrote a lot of dialogue that later remained, but structurally only one thing they did remained. And that was a masterpiece of an idea I thought. The second best idea in the whole movie.( report from what was additionally said in the interview for "Alien Evolution", 2001)  
3. Ron Shusett: They wanted that to be an army bunker for some reason, I guess they just, "okay this will give it realism", and that's boring, you can't, you know, once you're committed to that, you can't go back to a steel, you know, twentieth century army bunker. It's, it's, it's, it's er... that goes backwards in imagination where as that Giger design which he hand painted, airbrushed that whole wall himself personally, like he did his artwork, and that's why it looks so eerie, and and er the creature inside it too, the crew called Space Jockey. So that was one thing where they wanted realism, and then they said, "okay".  Ridley said, "no no, they can't use space things with realism like that, okay." Then they said, "we, more out there" and then they said something like, which sounds good on paper, but as you said, "we don't know the road not taken", their idea was somehow every past villain in history they would have to fight, somehow, Attila the Hun, ah, you know, ah, I can't even think of some of the classic, ah ah, classic monsters, not monsters, these were more human, famous historical villains, ah, that they would have to challenge at different times, not monsters, but people for, that were Hitler type people, people that were mass murderers, er, or or, some cases maybe a creature, but a creature that you, Jack the Ripper, well that was one of them. They wanted...
   Interviewer: What, are you talking about Alien?
   Ron Shusett: Yuh, so they, so that just threw it into a turmoil
   Interviewer: That's the craziest idea ever
   Ron Shusett: yes, pardon me
   Interviewer: That sounds like the craziest idea ever
   Ron Shusett: I know, it sounds crazy (http://www.askmrkern.com/page3.php October 27, 2012)