Science Fiction Bad Guys

[Noir]

Who is your favorite SF or Fantasy villain and why?

[quidproquo2004]

The Tines from "A Fire Upon the Deep".  They are not bad guys as such, but a very interesting alien developed by Vernor Vinge.  They were hive-mind creatures.  A particular "person" was made up of, say, five animals.  They communicated through a sort of high pitched speak.  I don't remember exactly, but when they get ahold of radio tech it becomes quite interesting.