Hey guy's and gals... info request..

I need a character.. preferably female who can be deemed immortal. And I
mean immortal to the point that she could probably outlast earth. My first
thought was A-Ko, but, is she immortal? Anywho, that's what I need... a
(preferrably female) immortal who could be expected to last for literally
BILLIONS of years....

Ray "The Texas Ryoga"