Tarkhan (Old Turkic Tarqan;Mongolian: Darkhan;Persian: ترخان‎; Chinese: 達干; Arabic: طرخان‎; alternative spellings Tarkan, Tarkhaan, Tarqan, Tarchan, Tarxan, Tarcan or Targan) is an ancient Central Asian title used by various Indo-European (i.e. Iranian and Tokharian) and Turco-Mongol peoples, especially in the medieval era, and prominent among the successors of the Mongol Empire.

The origin of the word is not known. Various historians identify the word as either Iranian (most likely East Iranian Sogdian or Scythian),Turkic, or Mongolian.

Although R. Frye reports that the word "was probably foreign to Sogdian", hence considered to be a loanword from Turkic, G. Doerfer points out that even in Turkic languages, its plural is not Turkic (sing. tarxan --> plur. tarxat), suggesting a non-Turkic origin. L. Ligeti comes to the same conclusion, saying that "tarxan and tegin [prince] form the wholly un-Turkish plurals tarxat and tegit" and that the word was unknown to medieval western Turkic languages, such as Bulgar. Taking this in consideration, the word is most likely derived from medieval Mongolian darqat (Mongolian plural suffix -at), itself perhaps derived from the earlier Sogdian word *tarxant ("free of taxes"). A. Alemany gives the additional elaboration that the related East Iranian Scythian (and Alanic) word *tarxan still survives in Ossetic tærxon ("argument, trial") and tærxon kænyn ("to judge").Harold Walter Bailey also proposes an Iranian (Khotanese Saka) root for the word.