The soul tourmented by Arthur Dent in The Hitchhikers Guide to the Galaxy. Arthur killed Agrajag, who was then reincarnated in another form, to be killed by Arthur again. lather, rinse, repeat.

Agrajag built a Cathedral of Hate in which to kill Arthur, but made the mistake of bringing him there too early, before Arthur killed him for the last time. Thus, it was quite impossible for Agrajag to actually kill Arthur, though he did try. Arthur inadvertently kills Agrajag in the process.