Guglielma Pallavicini (rarely Wilhelmina; died 1358), the Lady of Thermopylae, was the last Pallavicino heir to rule in Bodonitsa,[1] in Frankish Greece.

She shared the margraviate firstly with her mother Maria dalle Carceri and later with her stepfather Andrea Cornaro and her own husband Bartolomeo Zaccaria.

[2][3][4] In 1327, Guglielma Pallavicini married Bartolomeo Zaccaria, a Genoese man who had been captured during Cornaro's (and the margraviate's) repulsion of an invasion by Alfonso Fadrique of Athens.

Venice continued the dispute over Larena and sought the arbitration of the bailiff of Catherine II, Princess of Achaea, the legal suzerain of Euboea and Bodonitsa.

The Catalans, who had initially been asked to take no action, were now pressed by Venice to intervene for a peaceful settlement, along with Joan I of Naples, head of the Angevins, and Humbert II, Dauphin of Vienne (then a papal naval commander).

Guglielma still refused to readmit her husband to her court, preferring the advice of her own bishop Natarus of Thermopylae to that of the words of Pope Clement VI.