Margaretha Coppier or Margaretha van Kalslagen (1516, Alphen aan den Rijn – 1597, Breda) was a Dutch noble and a heroine of the Dutch war of liberation. Coppier was the daughter of Jacob Coppier, lord of Kalslagen and Alphen, and Margaretha van Roon. Her brothers and half-brothers all became active members of the Dutch rebellion. Coppier married Joachim Burgher, a polymath known as "Polites" from Goes, who before their marriage had become scribe of Antwerp in 1541. After his death in 1569 she married his successor as scribe, Willem Martini.