This has been a rumor for quite some time, but it finally came to a head early last week, which suggested that the most intense events in “The Walking Dead” series were part of a dream. The rumor stems from the lead character Rick Grimes (Andrew Lincoln) being in a coma in the series very first episode. Series creator Robert Kirkman wanted to lay this rumor to rest from his Twitter account.
“Rick is NOT still in a coma.”
This shadow theory has persisted for a long time, but came to a boil when an article was published on Uproxx that claimed that the character of Grimes had never woken up from his coma and that the series was taking place in his head. Kirkman tweeted.
Robert Kirkman ✔ @RobertKirkman
Going on record to answer this: http://uproxx.com/tv/2014/10/robert-kirkman-needs-to-go-on-the-record-promising-the-walking-dead-wont-end-as-rick-grimes-coma-dream/ … Rick is NOT still in a coma. The events of TWD are definitely happening.
Here is the article that started the ruckus in the first place.
Robert Kirkman Needs To Go On The Record Promising The Walking Dead… 
Robert Kirkman needs to go ahead and rule out a very popular ‘The Walking Dead’ theory now.
In spite of all the hoopla, Kirkman couldn’t resist teasing the fans and having a little fun with them when he tweeted this.
Robert Kirkman ✔ @RobertKirkman
But Carl and everyone else are all imagined. He actually NEVER found his family. He’s been crazy since he killed his first zombie. #joking?
The fifth season of “The Walking Dead” debuted on October 13th to its highest ratings to date. The show airs on Sundays at 8:00 p.m. Central/9:00 p.m. Pacific time on AMC. Check your local listings. The show stars Andrew Lincoln, Norman Reedus, Steven Yeun, Chandler Riggs, Danai Gurira, Melissa McBride, Lauren Cohen, Emily Kinney, Chad L. Coleman, Sonequa Martin-Green, Lawrence Gilliard, Jr., Michael Cudlitz, Alanna Masterson, Christian Serratos, Josh McDermitt, Andrew J. West and Seth Gilliam.
Sources: The Wrap, AMC