Official website: https://www.hbo.com/i-know-this-much-is-true
Mark Ruffalo
Dominick Birdsey / Thomas Birdsey
Melissa Leo
Concettina Ipolita Tempesta 'Ma' Birdsey
Rosie O'Donnell
Lisa Sheffer
Archie Panjabi
Dr. Patel
Kathryn Hahn
Dessa Constantine
John Procaccino
Ray Birdsey
Rob Huebel
Leo
Michael Greyeyes
Ralph Drinkwater
Gabe Fazio
Shawn Tudesco / Dominick and Thomas Acting Double