Movie adaptations of books are not good because they follow every word of the text. On the contrary, the greatest adaptations are more like translations of their source material. They find inspired ways to bring what works in one medium to another form of artistic expression, which includes changing details once thought indispensable by readers. So it was with 2001's "Shrek," a movie based on William Steig's 1990 children's book "Shrek!" The 30-page book is an exceedingly simple, albeit strikingly written and illustrated, work about a hideous ogre causing chaos in his pursuit of a princess that's as ugly as he is.
The appeal of building a story around an unabashedly grotesque character is immediately apparent, and it's no wonder the folks at DreamWorks Animation were captivated by this st