Celedonio Calatayud Costa (Spanish pronunciation: [?ele'ðonjo kalata'?uð 'kosta], October 29, 1880 in Pedreguer – January 24, 1931 in Madrid) was a Spanish scientist and radiologist, remembered for his achievements on radiology, radiotherapy, and electrology.
He pioneered the use of radiology and electrology in Europe for both diagnostics and therapeutical purposes, introducing radiotherapy in Spain in 1906.