The SCP Foundation is a secret organization dedicated to securing, containing, and protecting various anomalous entities. The website is an archive of top secret documents including entries for each entity, called an SCP followed by a number, containing a practical name, detailed description, the effects of the anomaly, experiments performed, containment methods, pictures, etc. Objects can be anything, benign looking household items, monsters, seemingly normal humans, etc. There’s nearly 5000 entries on the site. It’s a pretty fun time sink if you’re into short horror stories. Most of them only take a minute or two to read. There’s also multiple games, most notably SCP Containment Breach and tons of spinoff material.