HK-47, the Immortal

Protection from everything, Indestructible, Worldbound, Perpetual
"Statement: Then I will have to settle for your
screams"
"Statement: Oh, yes, Master. Pain is really the only reliable means by which truth may be obtained...
or so I choose to believe."
"Observation: I am a droid, master, with
programming. Even if I did not enjoy killing,
I would have no choice. Thankfully, I enjoy it
very much."