First Appearance: Marvel Mystery Comics #13 (November
Golden Age Appearances: Marvel Mystery Comics #13-48, Kid Komics #3.
Modern Appearances: Avengers #97, Invaders v2 #3-4, Marvels #1, 4 #1.
Years Active: 1942-1943? (see below)
During the Golden Age Aarkus, aka the Vision, was an alien policeman who came to Earth from another dimension to enforce justice. Well, that was his first origin, anyhow. As it turns out, the Timely books gave him not one other origin but two; which of the three you choose as canon is up to you.
The first alternate origin comes from a text piece in Marvel Mystery #23, in which it said that the Smoke World, Aarkus' homeworld, exists thousands of miles from Earth, in another dimension. (You're reading that correctly: thousands of miles from Earth, and also in another dimension.) The Vision was a "Keeper of Law" on that planet and was responsible for capturing the criminal (never named) who committed the first murder on Smoke World in centuries. The Vision, assisted by the "Law-Giver," Pearl Forrester, was looking for a suitable place of banishment for the murderer when he lucked into contact with an Earth scientist by the name of Markham Erickson. Erickson had pierced the spatial/dimensional barriers and asked the Vision to come to Earth to act as a super-powered guardian over humanity. The Vision's first attempt to come to Earth resulted in him going to Jupiter, where he left the murderer. He then came to Earth. It is said, in the text piece, that the Vision's race breathes smoke and that Smoke World has no houses, as its inhabitants use "pocket projection machines" to put themselves to sleep on the ground at their convenience.
The second alternate origin comes from Marvel Mystery #45. In that story Japanese agents travel to Shangri-La to obtain its secret of immortality. The Vision appears there to oppose them, claiming that he was the "first High Lama of Shangri-La." He says that he discovered the secret of immortality in Shangri-La, untold centuries ago, and that he made himself immortal, pledging himself to help the humanity. What he did after he left Shangri-La, or indeed when he left Shangri-La to begin with, is not mentioned.
His powers were erratically portrayed; most of the times he seemed to have no powers other than two good vists and his traveling-via-smoke, other times he seemed to be able to conjure up ice and whatever else he or the plot required.
His first appearance during the modern era was as one of several Golden Age heroes conjured up by Rick Jones in Avengers #97 to stop the Kree-Skrull War. Later it was revealed that during World War Two he'd fought crime, but had eventually been forced to work for the Nazis to stop the Invaders. They helped free him from the Nazis' thrall, and he helped the Invaders stop the Battle-Axis. Then, ashamed, Aarkus left for his home dimension. He has not reappeared in the modern era.
Note: Roy Thomas, in the second Invaders miniseries, claimed that the Vision was viewed with suspicion and mistrust by humans. This is not born out in the Timely stories, in which he was accepted by the public and usually treated in the same way that the public treated any other hero. Chalk this up as another one of Roy's Retcons.
Useful Vision Sites
The Vision. Eric Colley's site.
The Vision. Don Markstein's work.