SCP-035 appears to be a white porcelain comedy mask, although, at times, it will change to tragedy. In these events, all existing visual records, such as photographs, video footage, even illustrations, of SCP-035 automatically change to reflect its new appearance.

Subjects close to SCP-035, or in visual contact with it, experience a strong urge to put it on. When SCP-035 is placed on the face of an individual, an alternate brain wave pattern from SCP-035 overlaps that of the original host, effectively snuffing it out and causing brain death to the subject. Subject then claims to be the consciousness contained within SCP-035. The bodies of “possessed” subjects decay at a highly accelerated rate, eventually becoming little more than mummified corpses.

SCP-035 has proven to be highly sadistic, prompting some to commit suicide and transforming others into near-mindless servants with linguistic persuasion alone. SCP-035 has stated that it has intimate knowledge of the workings of the human mind and implied that it could change anyone's views if given enough time.

https://scpcb.gamepedia.com/SCP-035