Kuldar Sink (14 September 1942 in Tallinn – 29 January 1995 in Kõrve, Võru County) was an Estonian composer and flautist.
Some of the techniques he employed in his compositions included serialism, tone clusters, unified field, and aleatoric music.
In the latter part of his career he began incorporating traditions from the folk music of Central Asia into his compositions, and he ended his career with a period focused on choral works inspired by Gregorian chant and Estonian folk music.
He pursued graduate studies in music composition at the Leningrad Conservatory in the early to mid-1960s.
His most highly regarded composition is the song cycle Sünni ja surma laulud (The Songs of Birth and Death), which incorporates tonal and rhythmic elements of the Arabic classical music maqām.