A vizier ( /vɪˈzɪər/, rarely /ˈvɪzjər/; or وزير‎ in Arabic script (Persian, Urdu and Arabic); Hindi: वज़ीर ; sometimes spelled vazir, vizir, vasir, wazir, vesir, or vezir) is a high-ranking political advisor or minister in an Islamic government. The word derived from the Semitic root W-Z-R ('to help'); the word is mentioned in the Quran. The Abbasid Caliphs give the name title wazir to a minister formerly called Katib (secretary) who was at first merely a helper or henchman, afterwards became the representative and successor of the Dapir (official scribe or secretary) of the Sassanian kings.

In modern usage, the term has been used for ministers in the Arab world, Iran, Afghanistan, Pakistan, and India.

The word entered into English in 1562 from the Turkish vezir ("counsellor"), derived from the in Arabic wazir ("viceroy"). Wazir itself has two possible etymologies: on one hand it might be derived from āzara ("to help"), from the Semitic root W-Z-R ("to help somebody"); on the other hand, the presence of a Middle Persian predecessor for the word (in Pahlavi), vicir ("a legal document" or "decision"), derived from the Avestan vichira, meaning decreer or arbitrator, would seem to indicate an Indo-European origin. It is possible that the Semitic and Indo-Iranian terms influenced one another.