Konstantinos Panteleimon Kiassos (; born 13 December 1975) is a Greek former professional footballer who mainly played for OFI, as a midfielder.
Born in Chania, Kiassos has played for OFI, Panathinaikos, Iraklis, Numancia, Panionios, Anorthosis Famagusta, Levadiakos, PAS Giannina, Enosis Neon Paralimni, Panserraikos, Apollon Smyrni, Panachaiki and Welling United.
In 2019 he managed Agios Nikolaos.
In 2023 he became manager of Apollon Paralimnio.