Cognomen Хайду (Hajdu 
, Kaidu 
, Khaidu ) , all over the world, is a common surname. The family name Хайду is habitual in Eastern Europe, particularly Hungary, where it is a common surname, Slovakia, where it is quite a common surname, and Romania, where it is quite a rare surname. Much less frequently, Хайду is the forename as well as the last name.