Sijthoff may refer to:
People Albertus Willem Sijthoff (1829–1913), a prominent Dutch publisher Albert Georg Sijthoff (1853–1927), son of Albertus Willem Sijthoff and publisher of the Haagsche Courant Bob Sijthoff, descendant of Albertus Willem Sijthoff who sued Wikimedia in the Netherlands in 2008
Other 3201 Sijthoff, an asteroid named after Albert Georg Sijthoff Luitingh-Sijthoff, a Dutch publishing company passed down through the Sijthoff family Sijthoff Planetarium, a planetarium in the Hague that burned down in 1975