According to Michael Ausiello of Entertainment Weekly, various sources aren't mincing words:

Two key characters will die in this May's season finale.

And, no, these won't be pretend, Heroes-like deaths: a pair of lives truly will come to an end.

"These characters will die and they will stay dead," said a Smallville insider. "This is the real deal."

Let the guessing begin. Who do you think it will be?

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.