What was the name of Alexander's full sister?

Alexander’s full sister was Cleopatra of Macedon. She was the daughter of Philip II of Macedon and Olympias, making her Alexander’s only full sibling; his other well-known siblings were half-siblings from Philip’s other marriages.

Cleopatra was born around 355 or 354 BCE and grew up in the Macedonian royal court at Pella. Her family connections gave her substantial political importance. She married Alexander I of Epirus, her maternal uncle, in 336 BCE, the same year Philip II was assassinated. The marriage strengthened the alliance between Macedon and Epirus.

After her husband’s death, Cleopatra acted as regent of Epirus while her son was still young. Her position also made her a valuable potential bride after Alexander the Great died. Several of Alexander’s generals sought to marry her because marriage would provide a powerful dynastic claim.

Cleopatra is often confused with Thessalonike or Cynane, but both were Alexander’s half-sisters. Cleopatra of Macedon is also distinct from the much later Cleopatra VII of Egypt.