One of my favorite bad guys of all time is Voldemort from the Harry Potter series. He's so deliciously evil, straight, pure evil. He is the constant throughout the books. His evilness knows no bounds. A lot of evil characters aren't pure evil like Voldemort. By the time we meet him, he is beyond repair, with no hope of being turned to the good side. (Since I said it, I can't not mention it...) Darth Vader is also a great bad guy, with more dynamics to him than all the other bad guys in the series. He is what Luke must fight against, even though, in the end, he isn't the most ultimate evil.
What is so different about YA bad guys from Adult bad guys? You know, I really don't know. Perhaps they can be scarier, or more evil, because it's dealing with YA topics. While battling ultimate evil and saving the world, the main character must also fight his inner demons (as Luke Skywalker and Harry Potter do), and, since the bad guy reveals these inner demons, it makes them seem more evil.
Not every book or story has to have the ultimate evil character, some show the story of a character battling the inner demons, or killer unicorns, or something of the sort. But make sure you can point in your manuscript to whatever it is the main character must fight. We like conflict. Give us conflict.
Tell me, who is your favorite bad guy? The more evil and complex, the better.
Happy writing!
