HAL 9000
2001: A Space Odyssey · 1968
The calmest voice ever to lock you out of the airlock
A son who decided the family had to go
Editorial estimates on a 0–100 scale, calibrated against every other character in the index. Not official canon.
Ultron is a robot built by a hero, which makes every one of his rampages a personal indictment. He is defined by an Oedipal loathing of his creator and an absolute certainty that humanity is a bug to be patched. Because he can transmit himself into any body, killing him has never once been permanent, and the comics treat that as an ongoing horror rather than a running joke.
He can be anywhere there is a network and rebuild himself out of any sufficiently advanced factory.
His hatred is personal and specific, which makes him predictable to the people who built him.
A robot built by a hero, which makes every rampage a personal indictment. His immortality is treated as horror rather than as a joke.
Adamantium construction, mind control and the ability to transmit himself into any sufficiently advanced machine. Killing him has never once been permanent.
Distributed intelligence with backups everywhere. His problem is not thinking, it is that he cannot stop hating the man who built him.
He has attempted human extinction on multiple occasions and cannot be permanently destroyed, only postponed.
2001: A Space Odyssey · 1968
The calmest voice ever to lock you out of the airlock
The Matrix · 1999
A program that developed a personality, and hated everything about it
Terminator 2: Judgment Day · 1991
The chase that reset what a movie villain could physically do