Cotiso
Cotiso, Cotish or Cotison was a Dacian or Getic king who apparently ruled the mountains between Banat and Oltenia. Horace and Florus call him a Dacian; Suetonius calls him king of the Getae. Florus wrote in his account of Roman history that Cotiso and his armies used to attack towards south when the Danube froze.
Some scholars believe he is identical to Coson, a Dacian king whose name appears on gold staters found in Transylvania.
Background
After the death of Burebista, the Dacian kingdom fell apart amid turmoil and civil strife. Cotiso appears to have emerged as the dominant figure in Dacia at this time, but nothing is known about his background. The new king found himself courted by the two Roman antagonists, Octavian and Mark Antony. Cotiso was in a strong position to dictate terms of any alliance to either of the conflicting parties. Octavian/Augustus worried about the frontier and possible alliance between Mark Antony and the Dacians, and plotted an expedition around 35 BC. Despite several small conflicts, no serious campaigns were mounted. Cotiso chose to ally himself with Antony. According to Alban Dewes Winspear and Lenore Kramp Geweke he "proposed that the war should be fought in Macedonia rather than Epirus. Had his proposal been accepted, the subjection of Antonius might have been less easily accomplished."Proposed marriage
According to Appian, Antony is responsible for the statement that Augustus sought to secure the goodwill of Cotiso, king of the Getae by giving him his daughter, and he himself marrying a daughter of Cotiso. According to Suetonius, Cotiso refused the alliance and joined the party of Antony. Suetonius says Mark Antony wrote that Augustus betrothed his daughter Julia to marry Cotiso to create an alliance between the two men. This failed when Cotiso betrayed Augustus. Julia ended up marrying her cousin Marcus Claudius Marcellus.According to Dio, the story about the proposed marriages is hardly credible and may have been invented by Mark Antony as propaganda to offset his own alliance with Cleopatra.