In Japanese, 許 is transliterated as Yurusu, Bakari, or Moto and in Sino-Japanese as Kyo or Ko.

The Hoa people overseas Chinese of Vietnam with the surname 許 / 许 may have it spelled as Hái or Hy when immigrating to the English-speaking World, particularly the United States.

The surname 許 / 许 Xǔ has multiple theories regarding its origin.

One of the more credible ones states that the surname Xu originated from the feudal state of Xu in the area of Xǔchāng, now known as Jian'an District in Xuchang City,[1] of present-day Henan, during the Zhou dynasty.

A different theory states that the surname originated even earlier with the fabled Xu You (許由 / 许由), a sage in the time of the fabled Emperor Yao, not to be confused with the later another Xu You (許攸 / 许攸) who was a military strategist of the warlord Yuan Shao during the late Han dynasty.