It was Sheen's ex, Denise Richards who broke the news to the world on Twitter, congratulating the actor on the new member of his family.
I guess some of you have heard... @charliesheen is going to be a Grampa...yes GRAMPA! his beautiful daughter Cassandra is gonna be a mama..— Denise Richards (@DENISE_RICHARDS) January 15, 2013
Sheen, who is set to appear on the "Late Show with David Letterman" on Tuesday night, joked about his newest role during the interview.
“Me as a grandfather, Dave...I don't know. It's like the world's going to crack in half," Sheen said. "It's fabulous. It's just not a title I'm ready to adopt."