Family name Onysko (Onysko 
, Ониско 
, Онысько ) , all around the world, is a rare cognomen. The cognomen Onysko is characteristic of Eastern Europe, particularly Hungary, where it is a rare surname, Belarus, and Poland. Measured by absolute frequency, this name is the most popular in the United States, Poland, and Hungary. Much less frequently, Onysko is the forename as well as the last name.