Everything on Cerberus has died. Save for King Vinegaroon or however you spell it (the scorp in Altepa).
Many LS can kill the low tier HNM. The kings are killable by the major 5-6 NA LS's. CoP Wyrms; 3LS can kill Jorm (4th is getting really close), 2 can kill Tiamat and those two team up for Vrtra.
I have no knowledge of JP HNM LS's.
As for sea, 2-3 LS have a large chunk of their membership in Sea, and then there are some scattered people that have obtained access.