The Lord of the Rings:
The Two Towers

After watching The Two Towers, I was struck by how poorly this movie followed the book. I thought the changes in Tolkien's plot were absolutely gratuitous and were a slap in the face to all Tolkien fans.

One Orc

The loss of Merry and Pippin drinking from Treebeard's draughts.

Two Orcs

The loss of Erkenbrand and the shabby treatment of Eomer, who was forgiven by Theoden while still at Meduseld.

The loss of Gimli's retreat into the Caves of Aglarond, where he is to found another Dwarf kingdom.

The trick Merry has to play on Treebeard to convince the Ents to act.

Three Orcs

The loss of the Huorns, who are the ones who actually destroy Saruman's army, not the Rohirrim.

The loss of the argument between the Uruk-Hai and Mordor Orcs.

Four Orcs

The absolutely misbegotten change that Sauron (through Saruman's army) wants to commit genocide. Sauron wants to conquer Middle-Earth, not kill all humans. (Okay, he wants to kill the Numenoreans, but not all humans -- otherwise, why does he use the human Easterlings and Southrons?)

The silly "retreat" of all the Rohirrim from Meduseld to Helm's Deep. Will they make another forced march to Dunharrow in "The Return of the King"?

The utterly craven attitude of Theoden at Meduseld and Helm's Deep.

The presence of Frodo and Sam at the Battle of Osgiliath.

Five Orcs

The addition of the Elvish band at the Battle of Helm's Deep.

The utterly insipid treatment of Aragorn as the Wargs attack the fleeing Rohirrim. Getting stuck to a Warg, falling off a cliff, then a horse miraculously rescues him and bears him to Helm's Deep? Right.