Hetman is a political title from Central and Eastern Europe, historically assigned to military commanders. Used by the Czechs in Bohemia since the 15th century, it was the title of the second-highest military commander after the king in the Crown of the Kingdom of Poland and the Grand Duchy of Lithuania from the 16th to 18th centuries. Throughout much of the history of Romania and the Moldavia, hetmans were the second-highest army rank. In the modern Czech Republic, the title is used for regional governors.
Hetman Mikołaj "the Red" Radziwiłł
Hetman Jan Karol Chodkiewicz wearing a traditional costume of Polish magnates
Janusz Radziwiłł, one of the most powerful people in the Commonwealth at the time
Ukrainian Hetman Bohdan Zinoviy Khmelnytsky
Ataman was a title of Cossack and haidamak leaders of various kinds. In the Russian Empire, the term was the official title of the supreme military commanders of the Cossack armies. The Ukrainian version of the same word is hetman. Otaman in Ukrainian Cossack forces was a position of a lower rank.
Ivan Matveevich Krasnoshchekov, Ataman of the Don Cossacks. Portrait is from 1761. The term Ataman is a theme of various Russian folk songs (Watch Russian folk song where Ataman is the theme of the song on YouTube)