Leonardo Nam as Harlan Edwards: A gay CDC specialist who is Abby's second-in-command[1] Elle Graham as Susie Coyle: A young girl who is diagnosed with "Green Flu", appears to have a mysterious connection to Swamp Thing, and befriends Abby Given Sharp as Shawna Sunderland: Abby's childhood friend and Maria and Avery's deceased daughter, who appears in both flashbacks and as a ghost to her mother Maria Ian Ziering as Daniel Cassidy / Blue Devil: A former stuntman who, after becoming semi-famous after playing the demonic Blue Devil in a film, looks to regain his former fame[2] Selena Anduze as Caroline Woodrue: A scientist and Jason Woodrue's wife who has Alzheimer's disease Macon Blair as Phantom Stranger Al Mitchell as Delroy Tremayne: Liz's father Michael Beach as Nathan Ellery Steve Wilcox as Burritt Sunderland: Avery's father