that would be SCP-426; its entire wiki page is written as if the anomaly itself were writing it which is a really fun idea.
I only really mention 2086 (Man-Eating Bus), 4885 (Waldo), 3456 (Orcadian Horsemen), and 4666 (Yule Man) because of Alert World's extremely chilling EAS scenario videos on those specific four anomalies. They're especially scary to me because unlike 097 (which I just like based on vibes) they could all literally attack just because they feel like it and could do so whenever they want (relatively speaking since 4666 only manifests around December).