Subject 617

"Mmmm, fresh meat."

- One of the Hidden's few whispers to the IRIS troops

Subject 617, also known as The Hidden and The Stalker, is the titular main antagonist of the famous Half-Life 2 multiplayer mod The Hidden.

A team of scientists aligned to the Infinitum Research department went through years and years of experiments to modify and enhance the human DNA strain. Many test subjects were rendered either insane or dead from the experiments, and one of these poor individuals was Subject 617. While turned homicidally insane, he did not die, and was instead rendered extremely fast, strong, and almost invisible to the human eye, using these superhuman powers to escape and cause destruction.

The Infinitum Research Intercept Squad was then sent to hunt down and kill the psychopath, setting up the events of the game where one player controls 617 and the rest hunt him down before he strikes first.

Trivia

 * 617 is extremely similar to the titular antagonist of the first Predator film. Both are inhumanly fast and strong individuals who can turn invisible and brutally hunt down a team of soldiers. To even further prove the similarity, IRIS troops randomly say "If it bleeds, we can kill it," and "He is one ugly mother...", a pair of iconic quotes spoken in the first Predator film.