Greg Berlanti Open to More John Constantine on The Flash, Arrow and Legends of Tomorrow

Greg Berlanti says that while John Constantine's Arrow appearance is planned as a one-off thing, that doesn't mean he's saying the character won't make more appearances beyond the planned Season Four guest spot -- including possibly guesting on The Flash down the line.

"I've learned to never say never because so much has happened that I didn't think would happen with the characters and the shows and the universes that we're all getting to build and play in," Berlanti told Zap2it.

We'll see just how much screen time Matt Ryan's petty dabbler gets in a few months. Arrow returns for its fourth season -- in which Constantine will play a role in Episode Five -- on October 7 and will air new episodes Wednesday nights at 8 p.m. ET/PT on The CW.