Sibrandus Lubbertus (c.1555–1625) (also referred to as Sibrand Lubbert or Sybrandus Lubbertus) was a Dutch Calvinist theologian and was a professor of theology at the University of Franeker for forty years from the institute's foundation in 1585. He was a prominent participant in the Synod of Dort (1618–1619). His primary works were to counter Roman Catholic doctrine (especially that championed by Robert Bellarmine) and to oppose Socinianism and Arminianism.