DC Comics vs SCP Foundation
Connection:
Both are grey, hideous, destructive monsters who were raised in laboratories, but for one way or another crash landed on Planet Earth
Both have the unique ability to adapt to whatever tried to kill them the last time, they eventually reached a point where they became so powerful, not even their respective universes mightiest gods, monsters and demons are able to kill them permanently and halt their wrath.
Both are also infamous for their immense hatred for all living beings
