Worldwide, Тийу (Tiiu 
, Тийу 
) is a rare principally feminine, but very seldom masculine first name. The first name Тийу is habitual in Estonia, where it is quite a rare feminine name, Finland, where it is a rare girly name, and Australia. Not in comparison with a country's population, it is commonest in Estonia, the United States, and Australia. Very seldom, Тийу is the last name as well as the forename.