SCP Foundation (series)
The SCP Foundation is a collaborative fiction site and shared universe, focusing on the titular SCP Foundation, a shadowy, morally-ambiguous organisation which endeavours to catalogue and contain an unending array of “anomalies” — items, entities and locations with inexplicable and usually-dangerous supernatural properties.
Begun in 2008, it operates under a catch-all CC-BY-SA 3.0 license, making it one of the Jenny Everywhere mythos's most successful scions as an open-source online fiction framework. However, the two have only crossed over once, in 2018's SCP-JEv, an “unofficial” (not part of the official numbered list) SCP file for Jenny Everywhere herself, featuring an interview log of Jenny by minor recurring SCP character Doctor Fullham.