Alexander Jannaeus (Greek: Ἀλέξανδρος Ἰανναῖος Aléxandros Iannaîos; Hebrew: יַנַּאי‎ Yannaʾy; born Jonathan יהונתן) was the second king of the Hasmonean dynasty, who ruled over an expanding kingdom of Judea from 103 to 76 BCE. A son of John Hyrcanus, he inherited the throne from his brother Aristobulus I, and married his brother's widow, Queen Salome Alexandra. From his conquests to expand the kingdom to a bloody civil war, Alexander's reign has been generalised as cruel and oppressive with never-ending conflict. The major historical sources of Alexander's life are Josephus's Antiquities of the Jews and The Jewish War.

The kingdom of Alexander Jannaeus was the largest and strongest known Jewish State outside of biblical sources, having conquered most of Palestine's Mediterranean coastline and regions surrounding the Jordan River. Alexander also had many of his subjects killed for their disapproval of his handling of state affairs. Due to his territorial expansion and interactions with his subjects, he was continuously embroiled with foreign wars and domestic turmoil.