The Flintstones (cancelled Seth MacFarlane reboot animated series; 2013)
In early 2011, Family Guy creator Seth MacFarlane announced he would be reviving The Flintstones, but for a Fox audience, as he was a fan of the original series from the 60's. The first episode of the reboot was planned to air in 2013.
Little was known about the project for a while, even if it was still being developed or not. Production of MacFarlane's 2012 film, Ted, also made people believe it was cancelled.
When asked about the progress of The Flintstones at a convention to raise awareness about Ted, MacFarlane confirmed that whatever he had completed was shelved because Fox didn't think that an adult-oriented The Flintstones would be appealing to a large audience.
There is no more information about the project's development, and no element of whatever material has been made has been shown.