A.k.a. Dr. Dino
Kent Hovind needs no introduction, and plumbing the abyss of his cluelessness is probably not a hygienic enterprise, so we’ll restrict ourselves to the basics (and some examples). Hovind used to be the head of Creation Science Evangelism, a young earth creationist activist group. He also operated a small museum and amusement park known as "Dinosaur Adventure Land". In 2006, during the run-up to Hovind's trial for tax evasion, much of the park was shut down due to Hovind's refusal to secure a building permit. He was convicted on the tax evasion charges and is now serving a 10-year sentence.
Hovind has his doctorate in Christian Education from the diploma mill Patriot University. You can download his dissertation from this site (for instance); it was made public through Wikileaks and has become quite popular, so the server is often overloaded. It’s opening sentence, already established as a classic, is “Hello, my name is Kent Hovind”. In it he claims that “[i]n the twentieth century the major attack Satan has launched has been against the first eleven chapters of Genesis,” and goes on to display his deep understanding and erudite knowledge of modern biology by following it with “[c]hapter nine discusses the “best evidence” evolutionists have for evolution, that is, archeopteryx” and “I believe that dinosaurs are not only in the Bible, but the have lived with man all through his six thousand year history”, not to mention “The idea that evolutionists try to get across today is that there is continual upward progression. They claim that everything is getting better, improving, all by itself as if there is an inner-drive toward more perfection and order.” (More here, and here, and last but not least here)
Point is, Hovind views the manufactroversy between creation and evolution as an epic battle between God and his former chorus director, Satan. Evolution, you see, has been with us from the start: “When the people left the Tower of Babel, they took their false religion of evolution with them.” In fact, most opposition to Christendom concerns evolution: “the Islam religion accepts evolution very readily as a scientific fact because it fits so well with their teaching.”
Oh yes, Hovind believes the earth is 6000 years old, that the flood created Gran Canyon and that humans walked with dinosaurs. In fact Ken Ham, who shares these beliefs, has taken Hovind to task by creating a list of arguments against evolution a creationist should not use. They actually got into a dispute over that, since Hovind recognized several of his own trump arguments on Ham’s list. And that is Ken Ham. Of creation museum fame. When you are too ignorant of science for Ken Ham, then you are, well, rather ignorant. PZ Myers has attended one of his talks, and wasn’t particularly impressed.
So Hovind rejects the age of the earth, the field of astronomy, the entire field of geology, and has no trace of a clue about physics and/or radiometric dating. In fact, he is utterly ignorant of anything in science, has no time for evidence and is unmoved by facts. He doesn’t seem to mind, though. One famous example (among numberless) is his arguments against 'evolution' by trying to discredit the Big Bang, telling us that Big Bang violates the conservation of angular momentum because if everything came from a tiny spinning dot that blew up then everything would spin in the same direction; since some planets and moons in our solar system exhibit retrograde motion/rotation; this disproves the Big Bang, so evolution is impossible.
Other examples of his claims are that the Trail of Tears (1838) was a result of Darwin's Theory of Evolution (1859), that vaccinations are from Satan, that the New World Order was behind the Oklahoma bombings, that UFOs are “satanically owned and operated”, and that his commercial enterprises needn't file with the IRS in anyway or abide by legally issued warrants from same – even as a tax free organization in the unlikely event they qualify. With respect to this, Hovind claimed that as a minister of God everything he owns belongs to The Lord and he is not subject to paying taxes to the United States on the money he received for doing The Lord's Work (the judge in the case called his arguments “patently absurd”).
Hovind is well known for his "$250,000 Challenge", in which he states that he will pay $250,000 to anyone that can prove evolution. The conditions for “proof” are, well, Hovind’s own, and he has made it quite clear that it is logically impossible to meet his criteria (more here, and here).
An extremely fine resource on Hovind's studies can be found here. A nice, short summary can be found here. Note also this.
Kent has also lent his name to the Hovind, a unit of measurement which evaluates statements for kookery. Roughly, 0 is the score for a scientifically sound statement, 100 is for a lie that isn't even wrong. You can test your own Hovind here.
There are actually groups campaigning for Hovind’s release, such as this one (lead by one Adrienne Gilbert). Their main tactic seems to be praying, however, so they may be relatively harmless (here is another such call to prayer from the criminally insane Shelleytherepublican (Tristan Shuddery)).
Diagnosis: Hovind is a riot of insanity, ignorance, crackpottery, delusion, lunacy and idiocy. Thus, he has had rather far-reaching influence. His jail-time may have halted his career, and he seems to have grown even more unhinged during his time in prison. What happens when he is let out in 2015 will be interesting.