Sjaak is a given name. Notable people with the name include:
Sjaak Brinkkemper (born 1958), Dutch computer scientist, and professor
Sjaak Köhler (1902–1970), Dutch water polo player and swimmer
Sjaak Lettinga (born 1982), Dutch football (soccer) player
Sjaak Lucassen (born 1961), Dutch long-distance motorcycle rider
Sjaak Pieters (born 1957), Dutch track cyclist
Sjaak Polak (born 1976), Dutch football (soccer) player
Sjaak Swart (born 1938), Dutch football (soccer) player
Sjaak Rijke, Dutch national held hostage by a faction of Al Qaeda in the Maghreb region in Mali since 25 November 2011
Sjaak Troost (born 1959), Dutch football (soccer) player
