In 1999, a Swedish medical student brought ancient wizardry and horror fiction to life - despite being dead for three hours, Anna Bagenholm was revived and has made a nearly full recovery. 

It sounds cooler than D&D. Well, science often is - and what was happening in her body on a cellular level during the hours she went without a heartbeat, and what we can learn about how long it takes cells to die, may allow science to really push the boundaries of what it means to be dead.

As Miracle Max said in "The Princess Bride", there might be a difference between dead and mostly dead. 

If your cells hunker down in their outer membrane long enough for you to be "reanimated", then you will be - but the most vulnerable cells are those ones in the brain, which could be another mystery for science to pursue.

Read a terrifically fun piece, Is It Possible to Reanimate the Dead?, by Eli MacKinnon on LiveScience.