User blog comment:Gandalf1801/Question/@comment-26973802-20150708060530

I do not think there would be a new Dark Lord, the One Ring could have created a new one but it was destroyed with Sauron, and Wormtongue killed Saruman.

I'm not too familiar about Melkor since he was only mentioned once in the movies (Before Galadriel defeats Sauron she calls him "Spawn of Morgoth") but I seem to remember hearing he was banished to The Void and was killed by the spider Ungoliant, so pretty sure he's out of the way)