Anti-Monitor - Thanos with IG possibly with the HOTI
Darkseid - Thanos/ Galactus if DS is in his giant form.
A Luthor - This is a hard one.
Spectre - Living Tribunal
Parallax - Galactus/ Eternity
Mr. Mxyzptlk - IMO the only one in Marvel who would have a chance at stopping him is the LT.
Metron - Don't know.
Lucifer - Pre Retcon Beyonder is the only person I can think of.
Kismet - Kismet is meant to be DC's eternity but im not sure, she is a vague character
Shazam - Odin
I was told by some one ages ago the darkseid in comics is only an avatar and his true self is stuck in the source wall or something, I don't really know tbh. Has Kismet actually done anything in comics? Only time I ever seen her(?) was in OWAW and even then she had to merge with Supes to attempt and assault on Imperiex. Then people on here say things like she is the equivaliant of Eternity, fuk man I dont care.