By Martine Rothblatt, Philippe Van Nedervelde and the Lifeboat Foundation Scientific Advisory Board.
 
OVERVIEW

Methods of preserving persons — or just their personalities — include cryopreservation and uploading.
 
CRYOPRESERVATION

Regardless of what the threat is, in many cases the ability to weather the storm at cryogenic temperatures would allow time for the threat to blow over so that those at greatest risk can survive while those (or those mechanisms) in a better position to combat the threat at normal body temperature do so.
 
UPLOADING

A personality could be uploaded or migrated to a computer as well as being broadcast to the universe so a future ET could reinstantiate them in case an existential risk occurs. Instead of an ET, if one is willing to entertain either faster-than-light travel or non-Euclidean-space travel (e.g. wormholes), it may even be possible that our far-future descendants pick up our broadcasts and reconstruct us.
 
RESOURCES

Alcor Life Extension Foundation
 
Cryonics Institute
 
The Cryonics Society
 
CyBeRev
 
BOOKS

Fantastic Voyage : Live Long Enough to Live Forever by Ray Kurzweil and Terry Grossman - 2004