Another one - Eisenstein's Ivan the Terrible, part 3 - parts of which were filmed, and then later destroyed, but the filming of which was interrupted by the director's death.
To take it one stage further, in Underworld (DeLillo) there is an imaginary lost Eisenstein film which is found and shown.
"Artaud also had a theatrical project, entitled "The Conquest of Mexico" which he never got off the ground. But which I think parts of El Topo (or is the Holy Mountain?) are quite reminiscent of - especially the scenes of the conquest restaged as an invasion of war-frogs."
That's in The Holy Mountain.
"There's plenty of absurdity, not enough levity."
You don't think it's funny when he goes "You are your own master now - cut off my head"?
Either way I ought to get round to reading the book that's for sure.
Mangled films are another whole kettle of fish. I read somewhere that all the Paradjanov films had loads (literally hours) of extra footage and he had to basically create something out of what he had that would be acceptable to the authorities. I believe that one of his films had an entire gay storyline that was cut out of it.
Interesting to speculate about how different a film could have been with different editing. The classic one for this is Caligula I think. Brass took his name off the film as it was edited so much by the producers (he said he wanted to make a film about the orgy of power but they changed it to being a film about the power of orgy - whatever that means) and then it was further heavily censored differently in various countries so you had several different versions. I got the box set out of the video library the other day and there were about five different versions of the film in there - the one I watched was the longest and had, I think, all the footage that was available to insert - plus a load of extra hardcore porn that was shot later inserted just for good measure. Impossible to work out what the film actually should have been, it's hidden behind all the ones that came out I reckon.