Kostyantyn Masyk (Ukrainian: ????????? ???????? ?????) is a Ukrainian state official and diplomat.
Masyk was born in Volochysk on 9 July 1936.
A graduate of the Gorky Institute of Water Transport Engineers, his working career Masyk started at the Kiev factory of ship construction and repair in 1959-60.
In 1960s he became an activist of Komsomol of Ukraine becoming its first secretary in Kiev and Kiev Oblast.
In 1962 Masyk joined the Communist Party of the Soviet Union and finished the Higher Party School.
In 1970s he served on the party's positions in Kiev and Odessa.
In 1980s Masyk was a deputy chairman of council of ministers of the Ukrainian SSR and the First secretary of the Kiev city party committee.
In 1990-1992 Masyk was a first deputy chairman and vice-prime Minister of Ukraine and was acting head of government soon after ousting of Vitaliy Masol following the 1990 Kiev students' hunger strike.
In 1992–1997 he served as an ambassador of Ukraine to Finland and after that director of Nadra Bank.
Later Masyk joined Party of Regions.