| Musa | |
|---|---|
| Basilissa | |
 The portrait of Musa on the reverse of a Parthian drachm, Ecbatana mint | |
| Queen of the Parthian Empire | |
| Reign | 2 BC – 4 AD |
| Predecessor | Phraates IV |
| Successor | Orodes III |
| Co-ruler | Phraates V (2 BC – 4 AD) |
| Died | 1st-century AD |
| Spouse | Phraates IV |
| Issue | Phraates V |
Musa (also spelled Mousa), also known as Thea Musa, was a ruling queen of the Parthian Empire from 2 BC to 4 AD. Originally an Italian slave-girl, she was given as a gift to the Parthian monarch Phraates IV (r. 37 BC – 2 BC) by the Roman Emperor Augustus (r. 27 BC – 14 AD). She quickly became queen and a favourite of Phraates IV, giving birth to Phraataces (Phraates V). In 2 BC, she had Phraates IV poisoned and made herself, along with Phraates V, the co-rulers of the empire. Their reign was short-lived; they were forced to flee to Rome after being deposed by the Parthian nobility, who crowned Orodes III as king.
Musa is the first of only three women to rule as monarchs in Iranian history, the others being the two 7th-century Sasanian sisters Boran (r. 630–630, 631–632) and Azarmidokht (r. 630–631). Additional women, Rinnu, Ifra Hormizd and Denag, ruled only as regents of their sons and not as full monarchs in their own name.