Cave Johnson

Cave Johnson is the founder of Aperture Science, which was built from Aperture Science Innovations. Briefly mentioned in Portal he makes a more prominent appearance in Portal 2, in the form of tape recordings he leaves behind. His current status and whereabouts are unknown, presumed dead.

Shower curtains
In 1953 Cave Johnson sets up Aperture Fixtures, a shower curtain manufacturer. The precursor to Aperture Science, he chooses the name because it 'makes the curtains sound more hygienic'. He becomes a billionaire after winning contracts to manufacture the US Military's shower curtains.

Aperture Science Innovations
During his career in science, he called on the wealthy or power elite to join his cause for the future of science, as well as those with the brains, much like Caroline, and those lacking common sense for the dangers of science. Most of his ideas were wild and, more often than not, lethal. Some experiments involved replacing the test subjects blood with gasoline, while another exposed a tester to jet engines to lower the amount of water in the human body, stating it seemed 'excessive'. Most of his crackpot ideas turn out to be massive failures, leaving only a few that seem to be remotely useful. Ideas such as the gels that appear during the later stages of the game, namely Propulsion Gel and Repulsion Gel.

Aperture
At the time of creation, Aperture Science Innovations had created the Aperture Quantum Tunneling Device, a prototype to the modern Handheld Portal Device Chell wields. It seems Aperture had already begun to perfect the portal technology, but was not ready to unleash it to the world, thinking much more could be done than just portals. Of course, the technology was impractical and bulky, coupled with Cave's wild innovations. During the 70s, Aperture Science had become known as just 'Aperture', with the rise and competition of Black Mesa already putting Cave's temper to its limits. It was also around this time that Caroline became a bigger part of Cave's life as a secretary. It's also around this time where Cave becomes more desperate in his struggle to continue the life of his career and company through incentives, even if they were low-ball offers to lure potential test subjects to their doom.

Aperture Science
Sometime during the 80's, Cave Johnson had renamed the company Aperture Science, a name that would be known far into the future. However, the number of willing test subjects has dwindled over the years, and it grows to the point where employees and random strangers are pulled off the streets to be a part of the testing. The technology has advanced greatly, where robots are beginning to replace human employees. Said employees then become unfortunate victims of science in Cave's visions of the future of science.

During his final days, he states he had recently purchased a large amount of "moon rocks" for 70 billion dollars. However, his last few recordings indicate that Cave Johnson had fallen ill or has become extremely old. He explains that, in one of his wild ideas, he was smashing moon rocks together in the name of science since they acted as a great portal conductor, but it seems to have turned against him. The idea poisons him instead with a terminal illness with no cure, which slowly takes its toll on his body and mind. He had hoped to re-purpose the idea of making this 'moon gel' to create new portals that would sap the poison out of him, which results in the Conversion Gel. With little hope of a cure, he instructs his engineers to start research on (AI) and  in the hopes his brain can be downloaded onto a computer, stating they "should've been doing this 30 years ago". In the case he dies before the technology is released, he leaves instructions that his secretary Caroline will take charge of Aperture Science. He states that he knows she'll decline at first or feel she can't do it, which he follows up with "Force her to do it if you have to". It is unknown what becomes of him, but it is presumed he fell victim to the illness, and ultimately, to science.