Hi. John Stephenson is still listed with his voice agency and no obit can be found. While not always reliable, neither IMDb nor Wikipedia claim he's dead, let alone that he died in December 3012. If you have a reliable source, please post it. Thanks!
EDIT: Ah, I see the IMDb claim, which must have been made in recent days (I know, I looked at his page a few weeks ago) but there's nothing to back it up. Do you know of anything else? It's not impossible, but I find it highly questionable without anything else to source it. True voice actor passings can be swept under the rug at times, but it seems unlikely for someone like John Stephenson (and he knew and worked with enough people who can easily be contacted, like Mark Evanier or Corey Burton, that it's surprising that not one would have mentioned it). IMDb for several weeks or months at one point claimed Gregg Berger was dead.
Okay, I found one mention on a Western blog, but no actual obit, death certificate, etc. Again, it's not impossible, but I sent an e-mail to a voice director who worked with John Stephenson to see if he knows anything. Stephenson's demo is still up at his agency's website here, and while it has happened before, it's still odd to keep a deceased client's demo up for nearly a year.