Publisher's Weekly recently tweeted that William Sleator passed away in Thailand on Tuesday, August 2nd. He was 66.
I am a big fan. My default online handle, TychoTithonus, is the name of the main character in his book The Green Futures of Tycho.
I emailed with him a few times, and he signed one of my copies, but I regret that I never met him in person.
His work struck a chord with me in ways that are hard to explain. Some part of my childhood is now written in stone.
Other links about his passing:
Update 2011-08-07: William Sleator's obituary in the New York Times.