Rumor: Bryan Cranston was secretly cast as Lex Luthor and WB was waiting until Breaking Bad ended to make the announcement.
Source: Cosmic Bullsh** News
Investigation: This was on Cosmic Book News. Did it actually need an investigation? Of course, that didn't stop a few websites from taking the story and running with it.
Counter: Cranston was asked about it in an interview and he sounded open to the idea. Plus, he played a bald criminal scientist, SO IT MUST BE TRUE!!!!
Conclusion: After Breaking Bad ended, no announcement came, and CBN eventually released
this story admitting that they made the whole thing up claiming Cranston got "cold feet" and exited the project. A little while later, Jesse Eisenberg, an actor HALF CRANSTON'S AGE, was cast as Lex Luthor, further confirming the fact that this rumor was horsesh**.