The Virus is the secondary antagonist in the Architectverse series, Jeff Woods.
The Virus is an alternate take on the Slenderman and is the incarnation of him in the Architectverse. He is a brainwashing entity with malevolent intentions and is frequently seen protecting his creation from Derek and other threats. Initially appearing as a menacing figure in Eradicate.avi, his true form was not revealed until Protection at the end of the video, "attacking" Derek and Chris after the fight between them and Jeff.
He also makes a non screen appearance everytime when the camera distorts, like in the video DeathofJeff;-__'BirthofJeff|, where he causes Jeff to drastically switch between his good and evil personality.