I.M. Meen/WMG

I.M. Meen gets his powers from Satan, or some other evil entity.
Besides the demonic beasts that lurk in his labyrinth, he mentions that his book is "A nasty kind of a magic from a special kind of guy". Who that "guy" is is unknown- he could just be talking about himself, given his massive ego, but its not 100% clear.
 * Perhaps he actually meant "a special kind-of-guy."

I.M. Meen is the Joker's grandfather
Meen is where the Joker gets his love of purple tailcoats, maniacal laughter and just plain insanity from, and they have a similar facial structure too.

I.M. Meen is related to Jareth.
Both make children go through a magical labyrinth, both love to dance, and both have wild hair, among other things.

I.M. Meen is the Phantom of Flying Rhino Junior High
Both like torturing schoolchildren by sending them through a dangerous environment, both like wearing purple, both have henchmen which are pretty much useless at evil schemes, they even sound similar. Either the Phantom posed as Flying Rhino's librarian after using his Environmaster to disguise himself to trap kids in a magic book he found, Meen is who the Phantom will become in his old age, or Meen created the Environmaster as a new way to further torment kids, and disguised himself as the Phantom because he doesn't like the new fame he's got.

I.M. Meen's library contains not only the book that Link threw at Ganon, but also the enclosed instruction book
What other eldritch literature could be contained within his library?

I.M. Meen is a Ninja.
He is prone to disappearing and appearing in puffs of smoke, not unlike the Body Flicker Technique.

After the destruction of his labryinth, Meen had a delicious meal of roast warthog....
Why wouldn't he?

I.M. Meen hates the idea of a child surpassing him in magical power.
Hence the reason why is he so adamant about children learning and reading. He wants to keep them from learing magic and overtrow his tyranical rule.

I.M. Meen was a horrible student and is jealous of clever children.
His own magic powers don't seem all that hot, apparently. He probably was a lazy and terrible student at his magical school, dropped out having barely learned anything, and has been jealous of good students ever since.

The book that sucks children into the labyrinth is House of leaves..
It's already been stated that the book (House of leaves) is the labyrinth.

I.M Meen dropped out of Hogwarts
The book is just some magic artifact he stole.

I.M Meen hates children because of bad memories as a regular librarian
Meen was probably a librarian at a school specifically designed for know-it-all wizard children who appeared to be nice (or, goodie-goodies in Meen's terms) but hid their true nature; know-it all wizard children who often acted like assholes because of their superior magic and treated Meen like crap because of his notably less than impressive magic level while taking books from the library and never bringing them back. This is why he's so adamant against kids actually learning things and good-natured kids in general; he doesn't believe that smart kids are capable of being genuinely nice.
 * In other words, he was eventually led to believe that Dumb Is Good.

I.M Meen is Librarian of Unseen Academy before turning into monkey ape
He has magic power, has Tome Of Eldrich Lore and lives in library. What else do you need?

I. M. Meens book is the same as CD-i Link used in The Faces Of Evil.
Both of the books suck others inside.
 * Not only which, but...
 * Does this make Ganon a goodie-goodie bookworm?
 * More importantly: Does this mean CD-i!Link grew up to become IM Meen? (this is just ASKING for a Crack Fic)

I.M. Meen is related to the reader, Ipo.
They both seem to know a lot about books that suck people inside them.

I.M. Meen is gay and in the Transparent Closet. His "wife" is The Beard.
Seriously, Meen couldn't get more flaming unless he was on fire. He has a high voice, he lisps, and he dances around for no real reason. That, or he's Camp Straight.

IM Meen is much smarter than he looks.
He really is the most powerful magician in the world...what's to say that he didn't have his own reasons for letting you leave?