There are spoiler alerts in the below link, but it’s oh so worthwhile just to read the phrase at the end: “Schrödinger’s Glenn.”
(I am so unhappy I didn’t think of that).
I’m not as far along in the books as the author (I have to wait for the ebooks to be available from my public library), but it’s an interesting take on how/why Glenn might be alive.
Trivia: this is the second TWD actor to come from Supernatural’s first few seasons. The other: Lauren Cohan as Bella.
(Other trivia: two Supernatural actors were in seasons of Charmed, there are several two-step degrees of separation from Supernatural to Heroes.)
Warning: The addition of Jeffrey Dean Morgan (be still my pounding heart) may signal the end of my literary objectivity with regards to TWD and my unseemly and shameless entry into the world of girly- sighing, eyelash-fluttering, dreamy-eyed FanGirl-dom.