In a group with a history of cosmic occurrences, here’s one that took place way back at the beginning.  

The band needed a new name.  They’d just discovered the name they’d been using was already taken, so they spent two or three weeks throwing ideas back and forth.  Thousands of them according to Jerry Garcia.  

Then one fateful day as they were sitting around Phil’s house, smoking DMT, Jerry opened up a dictionary, and there on the page in front of him in bold letters was the phrase “grateful dead.”  In his mind-expanded state, he says, “the rest of the page oozed away and those two words were outlined in gold:  grateful dead.”

It was an entry describing a certain kind of folk tale, one in which the restless spirit of a maligned corpse returns to repay a kindness bestowed upon the body by the hero of the story.  

Lyricist for the Dead, Robert Hunter, found the choice to be exquisite.  “The evocative power of that strange, not at all comical name is considerable, for grace and [for] ill.  I know that my own input into the scene, my words, were heavily conditioned by that powerful name.  It called down sheaves of spirits on us all.”

. . . .

(Source:  dead.net)