The surname Butensky is a Jewish family name that originates in present-day Belarus (previously known as Belorussia, or "White Russia"). Since Belorussia was part of a larger territorial arrangement, the Grand Duchy of Lithuania, the Jewish communities of Belarus were part of the larger, Lithuanian Jewish culture.
Most people who descend from this family have ancestors who came from towns such as Slonim, Baranovich, Devoretz, Zhetl, and Derechin--although the original family itself probably has this name because of its origins in the town of Byten (theory).
These towns are located near each other, not far from Minsk, and were part of the venerable culture of Lithuanian Jewry. There are descendants of the Butensky family in many countries including the United States, South Africa and Israel.
Upon arrival in the United States, many Butenskys changed their surnames to such names as Burton, Buetens, and Butt (don't laugh; we want everyone's participation!)