Cadell ap Gruffydd (died 1175) was prince of the Kingdom of Deheubarth in Southwest Wales.
Cadell was the son of Gruffydd ap Rhys, who held part of the Kingdom of Deheubarth with the remainder in the hands of various Norman lords.
When out hunting, he was attacked by a Norman force from Tenby, who left him assuming him to be dead.
In 1153 he left on a pilgrimage to Rome, leaving the rule of Deheubarth to his younger brothers Maredudd and Rhys.
Cadell is not heard of again until 1175, when he entered the abbey of Strata Florida after a long illness and died there.