I use "illustrations" loosely here because these are all just stills from the anime. Isn't it crazy that they did this twice?
Anyway, I don't know if these are in the right order or not. I'm still just going by file names here, so if it's messed up please tell me.

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Taken from Horus Urusei Eye, a website that was dedicated to hosting Urusei Yatsura official art but has been offline for quite some time now. The site also hosted a bunch of other things such as art of other Rumiko Takahashi works, TV show theme songs, and the host's own weird fetish edits. These have not been preserved as well as the UY aspect of the site, so they may as well be lost to time.
If anyone has a larger backup of Horus Urusei Eye or has found it under another domain, please PM me!