The Hecatomnid dynasty or Hecatomnids were the rulers of Caria and surrounding areas from about 395-334 BCE, after Caria had left the Athenian alliance called the Delian League and returned under the control of the Achaemenid Empire. Before that, during the first period of Achaemenid rule, Caria was governed by the Lygdamid dynasty (520-450 BCE).
The Hecatomnids were nominally satraps (governors) under the Achaemenid Empire, but ruled with considerable autonomy, and established a hereditary dynasty. The dynasty was founded by Hecatomnus and originally had its seat in Mylasa; Mausolus moved it to Halicarnassus.
Hecatomnus' five children succeeded him in succession. The dynasty engaged in sibling marriage, presumably to preserve royal power within the family.
The best-known monument of the dynasty is the Mausoleum that Artemisia II built in honor of her husband and brother Mausolus.
After the death of Pixodarus, the last member of the Hecatomnids, Orontobates was sent by the king of Persia to succeed him. Orontobates, a Persian, married the daughter of Pixodarus, and ruled from 335 to 334.