You'll probably have to narrow it down a bit, carver. We've got some pretty uber entities like Spectre, Phantom Stranger, The Seven Deadly Sins, and Blight on DC earth at the moment.
Although if you're inquiring solely about the non-cosmic type who regularly inhabit earth, then in no particular order:
Constantine
Mr. E
Tannarak
Frankenstein
Swamp Thing
...Pretty much the JLD roster, and most baddies they've encountered.