Margareta of Sternberg (, ; died aft. 5 June 1365) was a Moravian noblewoman and by marriage Duchess of Bytom.
She was the eldest child and only daughter of Jaroslav of Sternberg (Jaroslav ze à  ternberka) by his second wife Margareta of BÃÂlina (Machna z BÃÂliny). Margareta had two full-brothers, Aleà ¡ and Jan, and also two older half-brothers, ZdenÃÂk (d. aft. 1408) and Smil (d. 1398), born from the first marriage of Jaroslav of Sternberg with a certain Elià ¡ka.
By 14 February 1347 Margareta married Duke Bolesà Âaw of Koà ºle. The marriage produced three daughters: Elisabeth âÂÂby marriage Duchess of CieszynâÂÂ, Euphemia âÂÂby her first marriage Duchess of Niemodlin and by the second Duchess of ZiÃÂbiceâ and Bolka âÂÂlater Abbess of TrzebnicaâÂÂ.
In 1352, Duke Bolesà Âaw inherited the Duchy of Bytom but died suddenly in Italy three years later (1355). In his will, he left Bytom to Margareta as her dower; however, the disputes soon began over the inheritance of the Duchy of Koà ºle-Bytom between the Dukes of Oleà Ânica and Cieszyn, who claimed rights by virtue of the treaty signed between Duke Wà Âadysà Âaw of Bytom and the Bohemian Kingdom, under which the succession of women over the Duchy in absence of male heirs was allowed. Koà ºle was taken by Duke Konrad I of Oleà Ânica (who claimed the rights of his wife Euphemia, eldest half-sister of Bolesà Âaw). At consequence of this conflict, Margareta's rights over Bytom were disputed and her rule was only formally.
After two years of conflicts, on 8 December 1357 a settlement was made: Bytom was divided between the Dukes Konrad I of Oleà Ânica and Casimir I of Cieszyn, legal guardian of Bolesà Âaw's daughters, who were forced to renounce their rights over the Duchy. Three years later, in 1360, the new Duke of Cieszyn, Przemysà Âaw I Noszak, married Elisabeth, the eldest daughter of Bolesà Âaw, and with this acquired additional rights over the half of Bytom. Margareta died five years later.