Family name Онищук (Онищук 
, Onishchuk 
, Onishuk 
) , in the entire world, is a common cognomen. The family name Онищук is characteristic of Eastern Europe, particularly Ukraine, where it is quite a common surname, Belarus, where it is quite a rare surname, and Russia.
| VARIANT | COUNTRY |
|---|---|
| Онищук | Ukraine, Kazakhstan, Belarus, Russia, Poland |
| Onishchuk | Ukraine, Canada, Belarus, Russia, United States |
| Onishuk | United States, Ukraine, Georgia |
| Onischuk | Canada, Uzbekistan, Belarus, Russia, United States |
Onichtchouk, Oniscuk, Onyshchuk, and Оніщук
| онищук, антон иванович UA (b. 1883) |
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| онищук василь онисимович UA (b. 1919) |
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онищук, светлана васильевна Ukrainian politician, UA (b. 1984) |
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| онищук василь варфоломійович UA (b. 1942) |
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| онищук, олег петрович Ukrainian Soviet military personnel, UA (b. 1961) |
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| владимир владимирович онищук Ukrainian chess grandmaster, UA (b. 1991) |
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Аля, Вера, Влад, Віта, Віра, Леся, Ліна, Ліля, Ліда, Ліза, Люба, Ляля, Олег, Илья, Инна, Иван, Емма, Егор, Саня, Сава, Саша, Соня, Ніла, Таня, Ніна, Неля, Аня, Ада, Зоя, Лев, Ева, Яна, Іра, Єва, Кіра, Макс, Майя, Алла, Анна, Адам, Поля, Петр, Дар'Я, Дина, Дима, Діна, Надя, Нина, and Тіна