I had posted this some days ago, only to discover that for whatever reason it did not take, so I will repost.
Karlheinz Stockhausen died in his home in Germany on 5 December. While I do not think that he is a great composer, or for that matter much of a composer at all, I do think that his work was enormously influential, giving rise to entire strains of electronic and ambient music. Moreover, he did have an effect on the Classical World, in both directions. He inspired those inclined to experimental music to go forth and experiment and he provoked a strong reaction against the atonalism and structural chaos of the post-modern school of composers.
I know Erik would disagree with me in this evaluation, and I welcome the retort, but maintain the stand. Stockhausen is a divisive figure. However, whatever he may be in the realm of the art himself, he was an essential catalyst and a genius of sorts. His influences has permanently shaped that face of music. Much of what comes after him (in the classical realm) will be in some way influenced by him, either by reaction or inspiration. When the art world loses such a figure, it is always a great loss.