Thomas de Melsonby (died after 1244) was a medieval Bishop of Durham-elect and Prior of Durham. Melsonby was the son of the rector of Melsonby. He was prior of a cell at Coldingham before being elected prior of Durham Cathedral in about 1233. He was elected to the see of Durham on 1 June 1237 but King Henry III of England objected. After lawsuits, Melsonby resigned the bishopric. He remained prior until 1244 when he resigned that office. He died sometime after 1244.