For one, we have the supreme evil in the series who is main villain throughout all six films (even though he shared this with Smaug and Azog in The Hobbit), extremely shadowy and menacing, and one of the most evil Dark Lords even more so than Palpatine and Voldemort put together, who is essentially Middle Earth's equivalent to the devil, and is nearly impossible to kill for a number of reasons. If it wasn't for Gollum, he would have won.
For another, we have the most annoying and pointless character, one of the snobbiest and greasiest characters in the series, who wasn't even in the book and was seemingly put there as the Middle Earth equivalent of Jar Jar Binks, only much meaner. Seemingly he got off a karma houdini (unlike his master), until the Extended Edition came out, and his karmic death ironically saves Gandalf.