Saruman

Saruman, aka Saruman the White, was a buddie of Gandalf until he turned evil for no particaulr reason. He was once a 'wise and powerful wizard' but when he turned against the good guys he decided to burn a load of forests which made Treebeard angry. Treebeard launched a massive attack on Isengard, where Saruman lived, and annihilated his army. Gandalf arrived soon later, only for Saruman to take a tumble off the Tower of Orthanc and die when he hit the bottom. Ouch.