Dad is a character created by Melanie Martinez for her debut album, Cry Baby. He was portrayed by Mughen Nakamura in Dollhouse, and it is unknown if he reprised his role in Sippy Cup.
Dad first appears in Dollhouse, where he is cheating on Mom with a "slut". In the song Sippy Cup, Mom discovers that he is coming home with his Mistress again, so she murders both of them.
Behind the scenes of Dollhouse.
Cry baby's dad can be seen in the bottom right hand corner with his mistress.