Sentella is the serpent goddess of good fortune. She is one of the gods worshipped on the planet Serepentis, and mentioned by Ash Graven in "The Grand Surrender".
According to Ash, people on Serepentis wait their entire lives in hope of seeing her just once.
The real Sentella is never seen, and it is thus unknown if she even exists. When the Team Squad was on Serepentis to look for one of the Dimensional Keys, KVN disguised himself as her in order to distract a large line of Pilgrims waiting to be sacrificed to Werthrent. Even though the disguise was crudely made and KVN couldn't get the name of the goddess right, the Pilgrims fell for it and chased after him in hope of getting good luck. KVN however lured them straight off a cliff, and they all fell to their deaths.