Don Alphonsus Ciacconius (born shortly before 15 December 1530, Baeza - died 14 February 1599, Rome) was a Spanish Dominican scholar in Rome.
His name is also spelt as Alfonso Chacón and Ciacono.
Chacón is known mainly for two of his works: Historia utriusque belli dacici a Traiano Caesare gesti (Rome, 1576), and Vitae, et res gestae pontificum romanorum et S.R.E.
Cardinalium ab initio nascentis ecclesiae usque ad Clementem IX.
P.O.M.
Alphonsi Ciaconii Ordinis Praedicatorum & aliorum opera descriptae (Rome, 1601).