Possibly the most influential and cited (though scarcely in peer reviewed publications – though he actually have a couple of those in mathematics) among America’s Intelligent Design creationists – and one of the most tireless, self-aggrandizing and seriously deluded. He is not a stupid guy, but there are things he is just completely unable to grasp, to the extent that it almost suggests some sort of cognitive malfunction (more likely confirmation bias and an inability to realize a mistake). See here, here, here, and here. No, he just doesn’t get it. Perhaps it is because his grasp of information theory is not as solid as it should be, resulting in some completely basic mistakes.
Ok, some background: Dembski has a Ph.D. in mathematics from the University of Chicago, and in philosophy from the University of Illinois at Chicago. Currently he pretends to teach at the Southwestern Baptist Theological Seminary (yes, pretends; his course requirements are, shall we say, dubious). He is quite clear that ID is science, not religion, as his quite clear from his own summary of ID: “Intelligent design is just the Logos theology of John's Gospel restated in the idiom of information theory.” Too bad Dembski doesn’t quite grasp the latter (some examples: here, and here). See also here.
He is closely associated with the Discovery Institute and is the mastermind behind the blog Uncommon Descent (UD, no link provided!); for more on his background, consult this objective article, or this one. He has gathered quite a substantial number of lackeys, including Denyse O’Leary, Dave Scott, Robert Marks, Barry Arrington (who now officially runs UD), Winston Evert, George Montañez and Bruce Gordon (all loons; some will have separate entries).
Most notable for his book “No Free Lunch” (which pretty much dresses Paley’s old fallacies up in math) and the never defined notion of “specified complexity” (here, here, here, and here, and an awesome post on creationist misuse of information theory in in general).
Dembski isn’t particularly good at handling handling criticism either.
Diagnosis: Seriously deluded kook who, despite being obviously intelligent, lets his own preconceptions completely obstruct his view as to how things actually hang together – even on topics related to his field of expertise. Extremely influential nonetheless, and as such extremely dangerous.