Hazan, Chazan, Chasen, Hasson, and Khazan are all alternative spellings of Hazzan, a Hebrew word carried over into most other Jewish languages that refers to the cantor in the Jewish prayer tradition.
Khazan is a Russian, Ukrainian, and Ashkenazi Jewish surname, and is a variant of the Hebrew 'Hazzan' and means cantor.
When spelled Khazan, the name has typically been transliterated from Cyrillic characters (Хазан), suggesting people of Russian-Jewish descent.
Hazan is a Turkish and Romaniote Jewish surname, and is a variant of the Hebrew 'Hazzan' and means cantor.
This variant is carried by the Romaniote Jews between Greece and Turkey.